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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## A satellite is composed of 30 modular units, each of... tagged by: BTGmoderatorLU ##### This topic has 3 expert replies and 0 member replies ### Top Member ## A satellite is composed of 30 modular units, each of... 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 The OA is D. I'm confused with this PS question. Experts, any suggestion about the solution? Thanks in advance. ### GMAT/MBA Expert GMAT Instructor Joined 08 Dec 2008 Posted: 12985 messages Followed by: 1249 members Upvotes: 5254 GMAT Score: 770 Top Reply LUANDATO 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 Since we're asked to find a certain FRACTION, we can plug in some nice values that meet the given conditions. Let's say that there's a TOTAL of 5 upgraded sensors on the entire satellite the number of non-upgraded sensors on one modular unit is 1/5 the TOTAL number of upgraded sensors on the entire satellite So, the number of non-upgraded sensors on EACH modular unit = (1/5)(5) = 1. Since there are 30 modular units altogether, the TOTAL number of non-upgraded sensors = (30)(1) = 30. So, the TOTAL number of sensors = (number of non-upgrades) + (number of upgraded) = 30 + 5 = 35 What fraction of the sensors on the satellite have been upgraded? = 5/35 = 1/7 Answer: D Cheers, Brent _________________ Brent Hanneson â€“ Creator of GMATPrepNow.com Use my video course along with Sign up for free Question of the Day emails And check out all of these free resources GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMATâ€™s FREE 60-Day Study Guide and reach your target score in 2 months! ### GMAT/MBA Expert Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 122 members Upvotes: 1153 GMAT Score: 770 Top Reply LUANDATO 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 The OA is D. I'm confused with this PS question. Experts, any suggestion about the solution? Thanks in advance. Or pick an easy number. Total # of upgraded sensors on 30 units. = 5. # of non-upgraded sensors on one unit = (1/5)*5 = 1 # of total non-upgraded sensors on 30 units = 1*30 = 30 Total # of sensors = 5 + 30 = 35. Upgraded/Total = 5/35 = 1/7- The answer is D _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

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LUANDATO 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

The OA is D.

I'm confused with this PS question. Experts, any suggestion about the solution? Thanks in advance.
Call the total # of upgraded sensors 'u.'
The # of non-upgraded sensors on one unit = (1/5)u
# of non-upgraded inits on 30 units = (1/5)u * 30 = 6u

If there are 'u' upgraded sensors and 6u non-upgraded sensors, then there would be 7u sensors in total. Upgraded/Total = u/7u =1/7. The answer is D

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