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A satellite is composed of 30 modular units, each of which [#permalink]
27 Aug 2011, 10:52

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Question Stats:

49% (02:20) correct
51% (01:10) wrong based on 186 sessions

A satellite is composed of 30 modular units, each of which is equipped with a set of sensors, some of which have been upgraded. Each unit contains the same number of non-upgraded sensors. If the number of non-upgraded sensors on one unit is 1/5 the total number of upgraded sensors on the entire satellite, what fraction of the sensors on the satellite have been upgraded?

Re: Satellite Sensors [#permalink]
27 Aug 2011, 18:56

11

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A satellite is composed of 30 modular units, each of which is equipped with a set of sensors, some of which have been upgraded. Each unit contains the same number of non-upgraded sensors. If the number of non-upgraded sensors on one unit is 1/5 the total number of upgraded sensors on the entire satellite, what fraction of the sensors on the satellite have been upgraded?

No of Units-30 Let there T-Total no of sensor U-no of upgraded sensors in one unit Nu-No of Not upgraded senor in one unit

Re: Satellite Sensors [#permalink]
26 May 2012, 20:49

Does anyone else find this problem hard to understand and translate into an equation? I understand it clearly after the explanation but I think it is poorly worded.

Re: Satellite Sensors [#permalink]
08 Oct 2012, 10:57

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This post received KUDOS

Cares wrote:

Does anyone else find this problem hard to understand and translate into an equation? I understand it clearly after the explanation but I think it is poorly worded.

Not really poorly worded, but maybe lengthy, and all those words, upgraded and non-upgraded... Annoying a little bit.

If N is the number of non-upgraded sensors in every one of the 30 units, and U is the number of those upgraded, we can write N = (1/5)*30U = 6U. This is the key equation, it is the translation of the information " ...the number of non-upgraded sensors on one unit is 1/5 the total number of upgraded sensors on the entire satellite...". So, we have U upgraded sensors and 6U non-upgraded ones, which means that the upgraded sensors represent U/7U = 1/7 from the total number of sensors. No need to multiply by 30, we are given that each unit has the same number of sensors of each type. Anyway, if you multiply by 30, it will cancel out and the final ratio is the same 1/7.

Answer D. _________________

PhD in Applied Mathematics Love GMAT Quant questions and running.

Re: A satellite is composed of 30 modular units, each of which [#permalink]
17 Jan 2013, 05:23

The question needs to be read very carefully and under timed conditions it's very easy to lose track with the wording; in the review of my Mgmat exam is ranked as 700-800 level by the way, so maybe it needs to be somewhat painful _________________

Re: A satellite is composed of 30 modular units, each of which [#permalink]
13 Apr 2014, 05:57

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Re: A satellite is composed of 30 modular units, each of which [#permalink]
13 Apr 2014, 22:10

Lets say total no. of upgraded sensors on whole satellite = 30 Then each module will have 1 upgraded sensor ......... (1) \frac{1}{5} th of 30 = 6 non-upgraded sensor on each module....... (2)

Re: A satellite is composed of 30 modular units, each of which [#permalink]
15 Apr 2014, 05:18

varunmaheshwari wrote:

A satellite is composed of 30 modular units, each of which is equipped with a set of sensors, some of which have been upgraded. Each unit contains the same number of non-upgraded sensors. If the number of non-upgraded sensors on one unit is 1/5 the total number of upgraded sensors on the entire satellite, what fraction of the sensors on the satellite have been upgraded?

A. 5/6 B. 1/5 C. 1/6 D. 1/7 E. 1/24

Thanks for the explanations on this question! It took me a while to understand this question - the wording kept throwing me off. I finally approached it as below:

There are 30 Units, each with multiple sensors.

Sensors are either U or NU Total number of sensors = total U + total NU

Given that total NU = 1/5 U; then 5NU = U Also, there are same number of NUs in each unit; therefore 30NUs in total

Now plugging into the first equation: Total sensors = 5NU + 30 NU = 35 NU

Question asks for total U/total sensors = 5NU/35NU = 1/7

Re: A satellite is composed of 30 modular units, each of which [#permalink]
30 May 2014, 10:04

varunmaheshwari wrote:

A satellite is composed of 30 modular units, each of which is equipped with a set of sensors, some of which have been upgraded. Each unit contains the same number of non-upgraded sensors. If the number of non-upgraded sensors on one unit is 1/5 the total number of upgraded sensors on the entire satellite, what fraction of the sensors on the satellite have been upgraded?

A. 5/6 B. 1/5 C. 1/6 D. 1/7 E. 1/24

A slightly different approach:

Let x be the number of non-upgraded sensors on a single unit (which is the same for all units). Therefore, there are 30x non upgraded units on the entire satellite.

We also know that the number of non-upgraded units on a single unit (which is x) is 1/5 the total number of upgraded sensors. Therefore, 5x equals the total number of upgraded units.

Thus, to find the fraction that have been updated, we simply take upgraded/total, which is 5x/ (30x+5x) = 5/35 = 1/7.

Answer: D

gmatclubot

Re: A satellite is composed of 30 modular units, each of which
[#permalink]
30 May 2014, 10:04