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
OAD
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
satelite
This topic has expert replies
-
j_shreyans
- Legendary Member
- Posts: 510
- Joined: Thu Aug 07, 2014 2:24 am
- Thanked: 3 times
- Followed by:5 members
GMAT/MBA Expert
-
Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Since we're asked to find a certain FRACTION, we can plug in some nice values that meet the given conditions.j_shreyans 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)1/2
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
= [spoiler]1/7[/spoiler]
= D
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
-
DavidG@VeritasPrep
- Legendary Member
- Posts: 2663
- Joined: Wed Jan 14, 2015 8:25 am
- Location: Boston, MA
- Thanked: 1153 times
- Followed by:128 members
- GMAT Score:770
Let's take the simplest possible scenario: we'll say that each of the 30 units has 1 non-upgraded sensor, giving us a total of 30 non-upgraded sensors on the satellite. We're told that the number of non-upgraded sensors on one unit is 1/5 the total of upgraded sensors on the entire satellite. If each unit has 1 non-upgraded unit, and '1' is 1/5 of the total upgraded sensors, then we must have a total of 5 upgraded sensors on the satellite.
In sum, on our satellite we have:
5 upgraded sensors
30 non-upgraded sensors
35 sensors total
So the fraction of upgraded to total is 5/35, or 1/7.
In sum, on our satellite we have:
5 upgraded sensors
30 non-upgraded sensors
35 sensors total
So the fraction of upgraded to total is 5/35, or 1/7.
-
DavidG@VeritasPrep
- Legendary Member
- Posts: 2663
- Joined: Wed Jan 14, 2015 8:25 am
- Location: Boston, MA
- Thanked: 1153 times
- Followed by:128 members
- GMAT Score:770
And I suspect the inspiration for this question was the following official question:
Alice's take home pay last year was the same each month and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of her monthly take home pay that she did not save. If all the money that she saved last year was from her take-home pay, what fraction of her take home pay did she save each month?
a. 1/2
b. 1/3
c. 1/4
d. 1/5
e. 1/6
Alice's take home pay last year was the same each month and she saved the same fraction of her take-home pay each month. The total amount of money that she had saved at the end of the year was 3 times the amount of her monthly take home pay that she did not save. If all the money that she saved last year was from her take-home pay, what fraction of her take home pay did she save each month?
a. 1/2
b. 1/3
c. 1/4
d. 1/5
e. 1/6
