If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take both o

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BTGModeratorVI: Legendary Member; Posts: 1223; Joined: Sat Feb 15, 2020 2:23 pmFollowed by: 1 member

by BTGModeratorVI » Mon Sep 14, 2020 8:43 am

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If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take both of them together to finish the job?

A. 160
B. 180
C. 200
D. 210
E. 220

Answer: C
Source: Kaplan

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Source: Beat The GMAT — Problem Solving | Mon Sep 14, 2020 8:43 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

Re: If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take bo

by Brent@GMATPrepNow » Thu Sep 17, 2020 6:08 am

BTGModeratorVI wrote: ↑
Mon Sep 14, 2020 8:43 am
If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take both of them together to finish the job?

A. 160
B. 180
C. 200
D. 210
E. 220

Answer: C
Source: Kaplan

GIVEN:
Carol can finish a job in 5 hours
Steve can finish the same job in 10 hours

A useful approach is to assign a "nice" value to the job.
We want a value that works well with the given information (5 hours and 10 hours).
So, let's say the entire job requires 10 tasks

This means Carol can complete 10 tasks in 5 hours. So, Carol's RATE = 2 tasks per hour
Similarly, Steve can complete 10 tasks in 10 hours. So, Steve's RATE = 1 tasks per hour

So their, COMBINED rate = 2 + 1 = 3 tasks per hour

How many minutes will it take both of them together to finish the job?
Time = output/rate
So, time = 10/3 = 10/3 HOURS

10/3 HOURS = (10/3)(60) MINUTES
= 200 MINUTES

Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Neha sharma: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Mon Jul 13, 2020 9:15 pmFollowed by: 1 member

Re: If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take bo

by Neha sharma » Thu Sep 17, 2020 9:43 am

1/5 + 1/10 = 10/3

10/3 * 60 = 200 mins
IMO C

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8155; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

Re: If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take bo

by Scott@TargetTestPrep » Mon Sep 21, 2020 6:26 am

BTGModeratorVI wrote: ↑
Mon Sep 14, 2020 8:43 am
If Carol can finish a job in 5 hours and Steve can finish the same job in 10 hours, how many minutes will it take both of them together to finish the job?

A. 160
B. 180
C. 200
D. 210
E. 220

Answer: C

Solution:

The rate of Carol is 1/5 of the job per hour and Steven 1/10 of the job per hour. Therefore, the time needed for both of them together to finish the job is 1/(1/5 + 1/10) = 1/(2/10 + 1/10) = 1/(3/10) = 10/3 hours, or 10/3 x 60 = 200 minutes.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]

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