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Quant Question of the Day Chat

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Quant Question of the Day Chat [#permalink]
PrabhatKC wrote:

­Although Brunuel and others used a matrix to solve this problem, a Venn diagram might be better because it's easier to conceptualize.  (Our brain prefers shapes/objects rather than numbers/words.)

Below is the initial Venn diagram.  Instead of using fractions, we stated that the total population is 100.  This is possible because we are dealing with relative proportions, so it won't affect the answer.  On the GMAT, converting fractions into whole numbers is an important strategy because it makes the problem easier to solve.  Constantly adding and subtracting fractions is very cumbersome and you could have wasted a lot of valuable time if you kept using fractions here.

We created two groups: 1. Rented (rooms that are rented) and 2. AC (rooms that have AC).

We know that the total number of rented rooms is 75 (3/4 x 100) and that the total number of rooms with AC is 60 (3/5 x 100).  We also know that 2/3 of AC is rented, so we put that fact into the diagram.

[See Venn 1]

Next, we calculate the exact amounts of rents that have AC.  We are also able to figure out that the number of rooms that are rented without AC is 15 because we subtract 60 (amount in the middle) from 75 (total rooms that were rented).  Given that the everything within the circles totals 95, we also know that the number of rooms outside the circle is 5.

[See Venn 2]

Final Step: What percent of the rooms not rented were air conditioned?

Rooms not rented = 20 + 5 = 25
Of these rooms not rented, the number with AC = 20

=> 20 / 25 = 80%

*Although I think a Venn diagram is the best method here, it's important that you know how to solve this problem using a matrix.  Sometimes, a matrix is faster or necessary, so also try solving this problem using a matrix.

If you would need individualized help, you can message me.­
­
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Quant Question of the Day Chat [#permalink]
krutikaaaa wrote:
can someone explain this question https://gmatclub.com/forum/edwin-is-pla ... 86309.html

can’t we just say total time T = 1500/ speed (edwin). splitting the time equally between two people = 1/2 * T which is 1/2*1500/speed(edwin). So the percentage reduction is 50% ? hence both statements are sufficient?

­
That's great that you're trying to think of this conceptually.  Unfortunately, you need to think deeper; go into more details.

If the time is split, it just means that both people are going to spend equal amount of time driving.  However, the total amount of time spent will not be reduced by 50%.  It may even increase!

Consider if the George drove at the same rate as Edwin.  Then they would get to Boston in the same exact time as before.  The amount of time spent traveling would be exactly the same, no?  Edwin would still be in the car with George.

Now, if the George happens to drive faster during his half of the drive, then the total traveling time would be reduced.

I think with these rate questions, it's best to write out the formula.

r (rate) x t (time) = d (distance).

If you apply the info given in the question, you get:

r(edwin) x t(edwin) = d

r(edwin) x t(half of together) + + r(george) x t(half of together) = d

(On the real test, abbreviate with letters such as "e" and "g" because it's much easier on your brain.)

Hopefully, writing out the equations this way, you can see that t(edwin) will be different than t(together).  You don't know what the ratio is unless you are given certain info.

My Assessment

Given your answer, it suggests that you need to take more time when confronted with questions/info.  This will improve your critical thinking skills not only on the GMAT but also in life in general.

For example, answer this question.  If you have a baseball and bat that costs together \$1.10.  The bat is \$1 more than the baseball.  How much is the baseball?­
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Re: Quant Question of the Day Chat [#permalink]
I need help here please 👇

A project is budgeted for 2400 hours and will last 3 weeks. Technicians will cover 25% of the project for the first week and then 60% for the final two weeks. If each technician normally works 40 hours per week, how many technicians are there?
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Re: Quant Question of the Day Chat [#permalink]
VictorAS wrote:
I need help here please 👇

A project is budgeted for 2400 hours and will last 3 weeks. Technicians will cover 25% of the project for the first week and then 60% for the final two weeks. If each technician normally works 40 hours per week, how many technicians are there?

Total hours: 2400 hours
Duration: 3 weeks

First week:
Technicians will cover 25% of the total project hours.
Hours in the first week = 0.25 * 2400 = 600 hours

Second and third weeks:
Technicians will cover 60% of the total project hours over these two weeks.
Hours in the second and third weeks = 0.60 * 2400 = 1440 hours
Hours per week (for 2 weeks) = 1440 / 2 = 720 hours/week

Calculating the number of technicians needed (each technician works 40 hours per week):

1. First week:
- Total hours needed: 600 hours
- Hours each technician works: 40 hours
- Number of technicians = 600 / 40 = 15 technicians

2. Second and third weeks:
- Total hours needed per week: 720 hours
- Hours each technician works: 40 hours
- Number of technicians = 720 / 40 = 18 technicians
- Since the number of technicians is constant throughout the project, the highest number of technicians required at any point is 18.
- Therefore, the number of technicians required is 18.
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Re: Quant Question of the Day Chat [#permalink]
hey

is this question really 655+?

Joan took out a mortgage from hel local bank. Each monthly mortgage payment she makes must be triple the amount of the previous month’s payment. If her first payment is \$100, and the total amount she must pay back is \$328000, how many months will it take Joan to pay back her mortgage?

Saw a post that it’s "650+" question, but it was in Gmat Classic:

"No, it’s not. I’d say it’s around 650 level question."

Were the difficulty converted correctly from Classic to Focus?
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Re: Quant Question of the Day Chat [#permalink]
GM everyone!
Please help me with this one.. A train travels 650km in 5 hr and another 940km in 10hr. What is the average speed of the train?
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Re: Quant Question of the Day Chat [#permalink]
Dexter43 wrote:
Total hours: 2400 hours
Duration: 3 weeks

First week:
Technicians will cover 25% of the total project hours.
Hours in the first week = 0.25 * 2400 = 600 hours

Second and third weeks:
Technicians will cover 60% of the total project hours over these two weeks.
Hours in the second and third weeks = 0.60 * 2400 = 1440 hours
Hours per week (for 2 weeks) = 1440 / 2 = 720 hours/week

Calculating the number of technicians needed (each technician works 40 hours per week):

1. First week:
- Total hours needed: 600 hours
- Hours each technician works: 40 hours
- Number of technicians = 600 / 40 = 15 technicians

2. Second and third weeks:
- Total hours needed per week: 720 hours
- Hours each technician works: 40 hours
- Number of technicians = 720 / 40 = 18 technicians
- Since the number of technicians is constant throughout the project, the highest number of technicians required at any point is 18.
- Therefore, the number of technicians required is 18.

These are the available options 👇

A. 22
B. 12
C. 40
D. 32
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Re: Quant Question of the Day Chat [#permalink]
Ave speed: Total Distance/Total Time = 1590km/15hr
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Re: Quant Question of the Day Chat [#permalink]
Krish13tss wrote:
GM everyone!
Please help me with this one.. A train travels 650km in 5 hr and another 940km in 10hr. What is the average speed of the train?

Total Distance = 1590 km
Total time = 15 hrs
Avg = 106
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Re: Quant Question of the Day Chat [#permalink]
GMAT.IQ wrote:

That’s great that you’re trying to think of this conceptually.  Unfortunately, you need to think deeper; go into more details.

If the time is split, it just means that both people are going to spend equal amount of time driving.  However, the total amount of time spent will not be reduced by 50%.  It may even increase!

Consider if the George drove at the same rate as Edwin.  Then they would get to Boston in the same exact time as before.  The amount of time spent traveling would be exactly the same, no?  Edwin would still be in the car with George.

Now, if the George happens to drive faster during his half of the drive, then the total traveling time would be reduced.

I think with these rate questions, it’s best to write out the formula.

r (rate) x t (time) = d (distance).

If you apply the info given in the question, you get:

r(edwin) x t(edwin) = d

r(edwin) x t(half of together) + + r(george) x t(half of together) = d

(On the real test, abbreviate with letters such as "e" and "g" because it’ll be easier on your brain.)

Hopefully, writing out the equations this way, you can see that t(edwin) will be different than t(together).  You don’t know what the ratio unless you have certain info.

My Assessment

Given your answer, it suggests that you need to take more time when confronted with questions/info.  This will improve your critical thinking skills not only on the GMAT but also in life in general.

For example, answer this question.  If you have a baseball and bat that costs together \$1.10.  The bat is \$1 more than the baseball.  How much is the baseball?

thank you for your explanation and your assessment too. Really appreciate it. About the baseball question, is the baseball worth 0.05\$ ? assuming the costs were for 1 bat and 1 baseball
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Re: Quant Question of the Day Chat [#permalink]
PrabhatKC wrote:
Is this the way?

Yes, it is correct.
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Re: Quant Question of the Day Chat [#permalink]
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Re: Quant Question of the Day Chat [#permalink]
MBAToronto2024 wrote:
hey

is this question really 655+?

Joan took out a mortgage from hel local bank. Each monthly mortgage payment she makes must be triple the amount of the previous month’s payment. If her first payment is \$100, and the total amount she must pay back is \$328000, how many months will it take Joan to pay back her mortgage?

Saw a post that it’s "650+" question, but it was in Gmat Classic:

"No, it’s not. I’d say it’s around 650 level question."

Were the difficulty converted correctly from Classic to Focus?

Oh Yeah! you are correct the ques is tagged under the 655 level which should be 700 plus level according to the classic version. But somewhere it has been mentioned that the level of the ques is 650 level (classic version) and should be in between 615 - 595 as per the new Focus version. I think this must be an error. I request the experts @Bunuel @chetan please see to it and rectify it. Thank you!
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Re: Quant Question of the Day Chat [#permalink]
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Re: Quant Question of the Day Chat [#permalink]
Second statement is clearly not sufficient as it is a set of positive numbers starting from 2 --- infinity. [ Clearly not sufficient]
and first statement n, n+1 both have 3 as not a factor [ Given ] so 100% n-1 will be divisible by 3

set of 3 consecutive integers are always divisible by 3 is 2,3 are not 100 % will be firsr
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Re: Quant Question of the Day Chat [#permalink]
Bunuel wrote:
Check here: if-n-is-a-po ... 00163.html

thankyouuu

prashi1503 wrote:
Second statement is clearly not sufficient as it is a set of positive numbers starting from 2 --- infinity. [ Clearly not sufficient]
and first statement n, n+1 both have 3 as not a factor [ Given ] so 100% n-1 will be divisible by 3

thankyou!

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Re: Quant Question of the Day Chat [#permalink]