If x persons take y day to complete z similar jobs, how long

Expert replies

Previous Topic Next Topic

BTGmoderatorLU: Moderator; Posts: 2650; Joined: Sun Oct 15, 2017 1:50 pmFollowed by: 6 members

by BTGmoderatorLU » Tue May 29, 2018 2:42 pm

Timer

00:00

Your answer

Difficulty–

right wrong

Pick an answer to see how members did

If x persons take y days to complete z similar jobs, how long does it take y persons to complete 1 such job?

A. z
B. x
C. x/y
D. z/x
E. x/z

The OA is E.

x person - z jobs in y days
x person - 1 job in y/z days
1 person - 1 job in y/zx days
y person - 1 job in y^2/zx
Am I missing something ?? Isn't the right way to do it ?? Can anyone assist me, please? Thanks in advance!

Source: Beat The GMAT — Problem Solving | Tue May 29, 2018 2:42 pm

GMAT/MBA Expert

Keith@ThePrincetonReview: Senior | Next Rank: 100 Posts; Posts: 38; Joined: Mon Mar 19, 2018 6:26 amFollowed by: 1 member

If x persons take y days to complete z similar jobs, how lon

by Keith@ThePrincetonReview » Tue May 29, 2018 5:12 pm

BTGmoderatorLU wrote:If x persons take y days to complete z similar jobs, how long does it take y persons to complete 1 such job?

A. z
B. x
C. x/y
D. z/x
E. x/z

The OA is E.

x person - z jobs in y days
x person - 1 job in y/z days
1 person - 1 job in y/zx days
y person - 1 job in y^2/zx
Am I missing something ?? Isn't the right way to do it ?? Can anyone assist me, please? Thanks in advance!

To remove any guesswork from the question, Plug In values for x, y, and z.

Let x = 2, y = 3, and z = 6, so that 2 people take 3 days to complete 6 jobs.
The question now asks how long it takes y = 3 people to complete 1 job.

If 2 people complete 6 jobs in 3 days, then 1 person completes 3 jobs in 3 days, or 1 job per day.
Therefore, 3 people working together can complete 1 job in 1/3 day.

Plug x = 2, y = 3, and z = 6 into each of the answer choices, looking for the choice that equals 1/3.
Choice A is z = 6, so eliminate choice A.
Choice B is x = 2, so eliminate choice B.
Choice C is x/y, or 2/3, so eliminate choice C.
Choice D is z/x, or 6/2, so eliminate choice D.
Choice E is x/z, or 2/6, so keep choice E.
The correct answer is choice E.

Jeff@TargetTestPrep: GMAT Instructor; Posts: 1462; Joined: Thu Apr 09, 2015 9:34 amFollowed by: 22 members; Location: New York, NY; Thanked: 39 times

by Jeff@TargetTestPrep » Thu May 31, 2018 3:21 pm

BTGmoderatorLU wrote:If x persons take y days to complete z similar jobs, how long does it take y persons to complete 1 such job?

A. z
B. x
C. x/y
D. z/x
E. x/z

We are given that x people take y days to complete z similar jobs. Since rate = work/time, we can determine the rate of x people:

rate of x people = z/y

To determine the rate for y people to complete 1 job, we can use a proportion to determine the rate of y people, in which n = the rate of y people. Our proportion read as:

“x people is to a rate of z/y as y people is to a rate of n”

x/(z/y) =y/n

xn = y(z/y)

xn = z

n = z/x

Since we have the rate of y people, we now can determine the time it takes for y people to complete 1 job.

time = work/rate

time = 1/(z/x) = x/z

Answer: E

Jeffrey Miller
Head of GMAT Instruction
[email protected]

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

Featured schoolRound 2 closes Jan 7, 2027 53 days left

Chicago Booth

Since 1982, 10 Booth faculty members have received the Nobel Prize in Economic Sciences, more than any other business school.

#3
U.S. News rank: $175,000
Median base salary: 670
Average GMAT Focus: 635
Students in the class

Apply to Booth Visit chicagobooth.edu See the full profile

Photo: Warren LeMay, CC BY-SA 2.0

GMAT Course Reviews

563 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (563 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review