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Traverton s city council wants to minimize the city s

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Traverton s city council wants to minimize the city s  [#permalink]

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New post Updated on: 16 Apr 2017, 18:44
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Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffic signal lights and so is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume significantly less energy and cost no more to purchase. Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal.

Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
(B) Whether any cities have switched from incandescent lights in their traffic signals to lighting elements other than LED arrays
(C) Whether the company from which Traverton currently buys incandescent bulbs for traffic signals also sells LED arrays
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffic signals know how to convert the existing fixtures so as to accept LED arrays

OG2017 CR553 P513

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Originally posted by mojorising800 on 20 Jan 2010, 03:46.
Last edited by hazelnut on 16 Apr 2017, 18:44, edited 3 times in total.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 31 May 2016, 20:21
7
paidlukkha wrote:
Why is D wrong?
I was stuck between A & D

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
we are evaluating but for me D looks more strong enough
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
council plans to increase the number, yearly costs wont minimize!


Comparison for Cost effecting solution is between incandescent bulbs and LED's. You got carried away by the statement "Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton"

Even if it plans to increase the number still the comparison will be between incandescent bulbs and LED's.

X number of LED are cost effective than X number of incandescent bulbs

Even if the city plans to increase the traffic lights say by a Factor of Y

Still X+ Y number of LED will be cost effective to X+Y number of incandescent bulbs. Does this all make sense to you?

Thus, D doesn't help us to reach anywhere.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 20 Jan 2010, 15:04
2
mojorising800 wrote:
7. Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffi c signal lights and so
is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the
incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume signifi cantly less energy
and cost no more to purchase. Moreover, the costs associated with the conversion of existing fi xtures so as to
accept LED arrays would be minimal.
Which of the following would it be most useful to know in determining whether switching to LED arrays would be
likely to help minimize Traverton’s yearly maintenance costs?
(A) Whether the expected service life of LED arrays is at least as long as that of the currently used
incandescent bulbs
(B) Whether any cities have switched from incandescent lights in their traffi c signals to lighting elements other
than LED arrays
(C) Whether the company from which Traverton currently buys incandescent bulbs for traffi c signals also sells
LED arrays
(D) Whether Traverton’s city council plans to increase the number of traffi c signal lights in Traverton
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffi c signals know how to
convert the existing fi xtures so as to accept LED arrays
]


Option A..... else reason "LED arrays consume significantly less energy and cost no more to purchase." would be nullified since LEDs would be bought and exchanged more freq than the incandescent bulbs!
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 29 Apr 2011, 07:54
another sub-400 level question. A is blatant
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 30 Jan 2016, 03:05
I got this wrong.

In option A) Whether the expected service life of LED arrays is at least as long as that
of the currently used incandescent bulbs.

The para states that LEDs consume significantly less energy and cost the same.

For example

Energy savings per year caused by the change from incandescent to LED = 1000000$
But LEDs last for 52 weeks, while incandescent last for 53 weeks.
The answer to the question, "Whether the expected service life of LED arrays is at least as long as that
of the currently used incandescent bulbs" is no here. But it would still make sense to shift from incandescent to LED, because the difference is less.

It significantly reduces energy consumption, so the only reason to not change from incandescent to LEDs would be if the service life of LEDs was significantly lesser than that of incandescent bulbs. It need not have a service life at least equal to that of incandescent.
It would be very important to know what the service lives of each of them are, so we can make a calculated decision. But the answer to the question - "Whether the expected service life of LED arrays is at least as long as that
of the currently used incandescent bulbs." tells us nothing.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 07 May 2016, 23:48
Why is D wrong?
I was stuck between A & D

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
we are evaluating but for me D looks more strong enough
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
council plans to increase the number, yearly costs wont minimize!
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Traverton s city council wants to minimize the city s  [#permalink]

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New post 16 Apr 2017, 18:42
1
mojorising800 wrote:
Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffic signal lights and so is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume significantly less energy and cost no more to purchase. Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal.

Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
(B) Whether any cities have switched from incandescent lights in their traffic signals to lighting elements other than LED arrays
(C) Whether the company from which Traverton currently buys incandescent bulbs for traffic signals also sells LED arrays
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffic signals know how to convert the existing fixtures so as to accept LED arrays


OG2017 CR553 P513

Traverton’s Traffic Lights
 
Step 1: Identify the Question

The phrase most helpful to know in determining in the question stem indicates that this is an Evaluate the Argument question.

Step 2: Deconstruct the Argument

Conc: replace bulbs with LEDs to << costs
b/c…
consume < energy
no more to purchase
not costly to change

The argument provides several cost advantages associated with switching to LEDs. Are there any other potential costs not discussed?

Step 3: Pause and State the Goal

On Evaluate questions, the goal is to find a piece of information that would be important to know to determine whether the conclusion is valid.

Step 4: Work from Wrong to Right

(A) CORRECT. The life of LEDs compared to current bulbs will affect how frequently they need to be changed and thus directly influence maintenance costs. If the life is about the same or LONGER, then switching may help to minimize costs. If the life is much SHORTER, however, then switching may cause costs to increase.
(B) The decisions by other towns to use LEDs do not affect the maintenance costs in Traverton.
(C) The source for purchasing incandescent bulbs versus LEDs does not directly affect costs.
(D) The number of traffic lights does not influence the relative costs of using LEDs versus incandescent bulbs. Each light source will still need a bulb.
(E) Whether the same crew can handle LED conversion does not have a direct impact on costs. Moreover, fixture conversion represents a onetime expenditure that will not influence ongoing maintenance costs.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 17 Apr 2017, 03:25
I chose D with below reasoning:
Although IB and LED arrays costs almost same, since energy consumed by LED arrays is less, this would help in minimizing T's yearly costs. If while increasing no of lights (as suggested in D), they use more LED arrays then my maintenance costs will be lower. What is incorrect with my reasoning?
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 17 Apr 2017, 05:00
The question asks to minimise yearly average costs. It does not ask whether the cost will increase/decrease from previous year

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New post 23 Apr 2017, 09:07
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adkikani,
Quote:
I chose D with below reasoning:
Although IB and LED arrays costs almost same, since energy consumed by LED arrays is less, this would help in minimizing T's yearly costs. If while increasing no of lights (as suggested in D), they use more LED arrays then my maintenance costs will be lower. What is incorrect with my reasoning?

As stated by ani007garg, we are asked, "Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?" Imagine that Traverton currently has 100 traffic signal lights and each of those lights costs $50 per year (ie cost of electricity) using incandescent bulbs (so $5,000 total in energy costs). Switching to LEDs might reduce the annual energy cost per light bulb to $40, bringing the total annual energy costs down to $4,000.
Quote:
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton

Now, what if, as suggested in choice D, Traverton increases the number of traffic signal lights from, say, 100 to 200? If they stick with incandescent bulbs, the total annual energy cost will be $10,000, but if they change to LEDs, the total annual energy cost will be $8,000. Yes, it is true that $8,000 is more than the original annual cost using incandescent bulbs ($5,000), but $8,000 is cheaper than $10,000; therefore, based on annual energy costs, switching to LEDs would indeed help minimize Traverton's yearly maintenance costs, regardless of how many bulbs they have (or plan to have in the future). Now, if those LEDs only last half as long as the incandescent bulbs, that means Traverton will have to spend more money replacing bulbs if they convert to LEDs. This additional cost might offset the energy cost savings, in which case switching to LEDs might not help minimize Traverton's yearly maintenance costs.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 22 Dec 2017, 05:04
mojorising800 wrote:
Traverton’s city council wants to minimize the city’s average yearly expenditures on its traffic signal lights and so is considering replacing the incandescent bulbs currently in use with arrays of light-emitting diodes (LEDs) as the incandescent bulbs burn out. Compared to incandescent bulbs, LED arrays consume significantly less energy and cost no more to purchase. Moreover, the costs associated with the conversion of existing fixtures so as to accept LED arrays would be minimal.

Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
(B) Whether any cities have switched from incandescent lights in their traffic signals to lighting elements other than LED arrays
(C) Whether the company from which Traverton currently buys incandescent bulbs for traffic signals also sells LED arrays
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
(E) Whether the crews that currently replace incandescent bulbs in Traverton’s traffic signals know how to convert the existing fixtures so as to accept LED arrays

OG2017 CR553 P513


OA is A but I have a kind of disagreement with. As it is given in argument "as the incandescent bulbs burn out"(means LED wouldn't burn out or better service life) is given the answer to Option A so further determining same thing is not be the correct option. IMO answer should be E.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 30 Dec 2017, 16:15
vksharma wrote:
OA is A but I have a kind of disagreement with. As it is given in argument "as the incandescent bulbs burn out"(means LED wouldn't burn out or better service life) is given the answer to Option A so further determining same thing is not be the correct option. IMO answer should be E.

I think you might be misunderstanding this part of the passage: "as the incandescent bulbs burn out". This means that WHEN an incandescent bulb burns out, it will be replaced with an LED (as opposed to replacing all of the incandescent bulbs all at once, regardless of whether they are burnt out).

The use of "as" in this sentence is similar to the following sentence: "As guests arrive, the hostess will take their coats." Here "as" is used to describe when something is happening. In this case, "as" is NOT used as a comparison (i.e. (just) as). I believe you interpreted this phrase to mean: "SINCE the incandescent bulbs burn out...."

As for choice (E), we need to determine "whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs". Even if we have to spend some money up front to retrain workers, this one-time up-front cost will not affect YEARLY maintenance costs in the long run. Besides, we are already told that the cost of converting the fixtures would be minimal. We also don't necessarily need the CURRENT crews to install the LEDs. Whether the bulbs are replaced by current crews or other crews, we need to know how the change will impact yearly maintenance costs. Choice (E) does not help.

And welcome to GMAT Club, vksharma!
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 01 May 2018, 00:39
honchos wrote:
paidlukkha wrote:
Why is D wrong?
I was stuck between A & D

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
we are evaluating but for me D looks more strong enough
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
council plans to increase the number, yearly costs wont minimize!


Comparison for Cost effecting solution is between incandescent bulbs and LED's. You got carried away by the statement "Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton"

Even if it plans to increase the number still the comparison will be between incandescent bulbs and LED's.

X number of LED are cost effective than X number of incandescent bulbs

Even if the city plans to increase the traffic lights say by a Factor of Y

Still X+ Y number of LED will be cost effective to X+Y number of incandescent bulbs. Does this all make sense to you?

Thus, D doesn't help us to reach anywhere.





I do not agree with your reasoning for option D here. Option D says plans to increase. That means they have not increased the number of traffic signals yet.
If you think that the city would first increase the number of bulb signals and then change those new bulb signals with the LEDs, then I guess it is non sensical to first add bulbs to the new signals and then replace them with LEDs.

Point here is the argument talks about average yearly expenditure which will remain same for even if you increase the number of traffic signals.

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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 13 Jun 2018, 01:38
honchos wrote:
paidlukkha wrote:
Why is D wrong?
I was stuck between A & D

(A) Whether the expected service life of LED arrays is at least as long as that of the currently used incandescent bulbs
we are evaluating but for me D looks more strong enough
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton
council plans to increase the number, yearly costs wont minimize!


Comparison for Cost effecting solution is between incandescent bulbs and LED's. You got carried away by the statement "Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton"

Even if it plans to increase the number still the comparison will be between incandescent bulbs and LED's.

X number of LED are cost effective than X number of incandescent bulbs

Even if the city plans to increase the traffic lights say by a Factor of Y

Still X+ Y number of LED will be cost effective to X+Y number of incandescent bulbs. Does this all make sense to you?

Thus, D doesn't help us to reach anywhere.



But don't you think it is foolishness to first use the bulbs in new traffic signal lights and then replace them with the LEDs. My point is LEDs with be X +Y and Bulbs will be X. Now how will you compare them?
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New post 03 Jul 2018, 05:20
GMATNinjaTwo wrote:
adkikani,
Quote:
I chose D with below reasoning:
Although IB and LED arrays costs almost same, since energy consumed by LED arrays is less, this would help in minimizing T's yearly costs. If while increasing no of lights (as suggested in D), they use more LED arrays then my maintenance costs will be lower. What is incorrect with my reasoning?

As stated by ani007garg, we are asked, "Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?" Imagine that Traverton currently has 100 traffic signal lights and each of those lights costs $50 per year (ie cost of electricity) using incandescent bulbs (so $5,000 total in energy costs). Switching to LEDs might reduce the annual energy cost per light bulb to $40, bringing the total annual energy costs down to $4,000.
Quote:
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton

Now, what if, as suggested in choice D, Traverton increases the number of traffic signal lights from, say, 100 to 200? If they stick with incandescent bulbs, the total annual energy cost will be $10,000, but if they change to LEDs, the total annual energy cost will be $8,000. Yes, it is true that $8,000 is more than the original annual cost using incandescent bulbs ($5,000), but $8,000 is cheaper than $10,000; therefore, based on annual energy costs, switching to LEDs would indeed help minimize Traverton's yearly maintenance costs, regardless of how many bulbs they have (or plan to have in the future). Now, if those LEDs only last half as long as the incandescent bulbs, that means Traverton will have to spend more money replacing bulbs if they convert to LEDs. This additional cost might offset the energy cost savings, in which case switching to LEDs might not help minimize Traverton's yearly maintenance costs.


Hi GMATNinjaTwo, would you please confirm whether my reasoning is valid.

I thinks D is hard to assess, because D say increase the number of lights, but how many ? we don't know. the prompt does not tell us.
suppose, increase 100 lights, the yearly maintain cost almost same, while increase 101 , the yearly maintain cost increase significant.
then as long as the increases are fewer than 100, then two paths( increase 1 light and increase 100 lights), then both results are almost same, (no matter increase 1or 100, the yearly costs are almost same)
once the increases are more than 100, then the yearly costs are almost same.

Please confirm

Thanks in advance.
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 06 Jul 2018, 17:37
zoezhuyan wrote:
GMATNinjaTwo wrote:
adkikani,
Quote:
I chose D with below reasoning:
Although IB and LED arrays costs almost same, since energy consumed by LED arrays is less, this would help in minimizing T's yearly costs. If while increasing no of lights (as suggested in D), they use more LED arrays then my maintenance costs will be lower. What is incorrect with my reasoning?

As stated by ani007garg, we are asked, "Which of the following would it be most useful to know in determining whether switching to LED arrays would be likely to help minimize Traverton’s yearly maintenance costs?" Imagine that Traverton currently has 100 traffic signal lights and each of those lights costs $50 per year (ie cost of electricity) using incandescent bulbs (so $5,000 total in energy costs). Switching to LEDs might reduce the annual energy cost per light bulb to $40, bringing the total annual energy costs down to $4,000.
Quote:
(D) Whether Traverton’s city council plans to increase the number of traffic signal lights in Traverton

Now, what if, as suggested in choice D, Traverton increases the number of traffic signal lights from, say, 100 to 200? If they stick with incandescent bulbs, the total annual energy cost will be $10,000, but if they change to LEDs, the total annual energy cost will be $8,000. Yes, it is true that $8,000 is more than the original annual cost using incandescent bulbs ($5,000), but $8,000 is cheaper than $10,000; therefore, based on annual energy costs, switching to LEDs would indeed help minimize Traverton's yearly maintenance costs, regardless of how many bulbs they have (or plan to have in the future). Now, if those LEDs only last half as long as the incandescent bulbs, that means Traverton will have to spend more money replacing bulbs if they convert to LEDs. This additional cost might offset the energy cost savings, in which case switching to LEDs might not help minimize Traverton's yearly maintenance costs.


Hi GMATNinjaTwo, would you please confirm whether my reasoning is valid.

I thinks D is hard to assess, because D say increase the number of lights, but how many ? we don't know. the prompt does not tell us.
suppose, increase 100 lights, the yearly maintain cost almost same, while increase 101 , the yearly maintain cost increase significant.
then as long as the increases are fewer than 100, then two paths( increase 1 light and increase 100 lights), then both results are almost same, (no matter increase 1or 100, the yearly costs are almost same)
once the increases are more than 100, then the yearly costs are almost same.

Please confirm

Thanks in advance.
>_~

zoezhuyan, the passage does not say that Traverton wants to DECREASE the city’s average yearly expenditures on its traffic signal lights. Regardless of how many light bulbs Traverton has, adds, or plans to add, we want to MINIMIZE the cost. In other words, given any number of bulbs, will the city’s average yearly expenditures on its traffic signal lights be lower if they switch to LEDs?

That was the idea behind this post. Sure, the total annual costs increased from $5,000 to $8,000. But if we had NOT switched to LEDs, the costs would have risen from $5,000 to $10,000. So even though the costs have increased, we have still minimized those costs. The number of bulbs that the city needs is not relevant to this argument. Also, the total change in costs (up, down, or neither) compared to this year is not important. Whether they add a single bulb or a million bulbs, we want to know whether switching to LEDs will minimize the annual costs.

I hope that makes sense!
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Re: Traverton s city council wants to minimize the city s  [#permalink]

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New post 07 Jul 2018, 01:04
GMATNinja wrote:
zoezhuyan, the passage does not say that Traverton wants to DECREASE the city’s average yearly expenditures on its traffic signal lights. Regardless of how many light bulbs Traverton has, adds, or plans to add, we want to MINIMIZE the cost. In other words, given any number of bulbs, will the city’s average yearly expenditures on its traffic signal lights be lower if they switch to LEDs?

That was the idea behind this post. Sure, the total annual costs increased from $5,000 to $8,000. But if we had NOT switched to LEDs, the costs would have risen from $5,000 to $10,000. So even though the costs have increased, we have still minimized those costs. The number of bulbs that the city needs is not relevant to this argument. Also, the total change in costs (up, down, or neither) compared to this year is not important. Whether they add a single bulb or a million bulbs, we want to know whether switching to LEDs will minimize the annual costs.

I hope that makes sense!


Thanks so much GMATNinja,
Now i got it. at first, i mistook minimize with reduce.
excellent explanation.

Have a nice day
>_~
GMAT Club Bot
Re: Traverton s city council wants to minimize the city s &nbs [#permalink] 07 Jul 2018, 01:04
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Traverton s city council wants to minimize the city s

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