A can complete a certain job in 12 days. B is 60% more efficient than

Question

A can complete a certain job in 12 days. B is 60% more efficient than A. In how many days can B complete the same job?

(A) 6
(B) 6.25
(C) 7
(D) 7.5
(E) 4.8

Little awkward explanation.60% more efficient means B can do 160% of work in same no. of days as A takes to do 100% of work.
160% work in 12 days
100% work in x days
x =  \frac{(12*100)}{160}

Bunuel · Accepted Answer

B is 60% more efficient than A, means that the rate of B is 1.6 times as greater as that of A.

So, if A can complete the job in 12 days, then B complete the same job in 12/1.6 = 12/(8/5) = 15/2 = 7.5 days.

Answer D.

P.S. Not exactly a GMAT wording.

GMATinsight · Answer

Alternate Method

Let, Total Work Unit = 120 Units

A can finish in 12 days = 120 unit work
i.e. A can finish in 1 days = 10 unit work
i.e. B can finish in 1 days = 10+(60/100)*10 = 16 unit work

Days in which B will complete the work alone = 120/16 = 30/4 = 7.5 days

Answer: Option D

reto · Answer

Set up a Rate Time Work Table and plug in the values:

Rate / Time / Work for A:
12 / 12 / 144

Rate / Time / Work for B:
19.2 / 7.5 / 144

Do not fall into the trap by just working with the time, i.e. taking 60% off from 12 days and subtracting it from 12.   Trap Answer E.

TimeTraveller · Answer

Let the number of units of work done by A in one day = 10, so B does 16 units of work per day.

Total units of work done by A = 12*10 = 120 units.

No. of days taken by B to do 120 units of work = 120/16 = 7.5. Ans (D).

matthewsmith_89 · Answer

You could even do process elimination

let's start with C

7 x 1 3/5
56/5 or 11 1/5 Not the answer. Let's use a big number

D - 7 1/2 x 1 3/5
15/2 x 8/5
12

The answer is D

JeffTargetTestPrep · Answer

The rate of A is 1/12.

Since B is 60% more efficient the rate of B is 1.6 x 1/12 = 1.6/12 = 16/120 = 2/15.

Since time is inverse of rate, B can complete the job in 15/2 = 7.5 days.

Answer: D

rsmalan · Answer

Hello there This is a good Problem Solving question testing concept of Work-time. Per given information, Work done by A in 1 day = \frac{1}{12} Because B is 60% more efficient, Work done by B = 1.6 x \frac{1}{12} Thus, time taken by B to complete the work = \frac{12}{1.6} = 7.5 days Answer (D) Is there anything I could clarify better in this solution? Pls share your thoughts. Thank you.

GmatPoint · Answer

Let A do 10 units of work every day.
Since B is 60% more efficient than A, B will do 16 units of work per day.

Also, as A can complete the work in 12 days, total work = 12*10 = 120 days.

Time taken by B to complete the same work = 120/16 = 7.5 days.

Thus, the correct answer is D.

Kinshook · Answer

Given: A can complete a certain job in 12 days. B is 60% more efficient than A. 
Asked: In how many days can B complete the same job?

B is 1.6 times as efficient as A.
B will take = 12/1.6 = 30/4 = 7.5 days to complete the same job.

IMO D

BritLee · Answer

Is it incorrect to add 60% of 12 to get 7.2, which is ~closest to the answer 7.5?

KarishmaB · Answer

The question can be solved quickly using percentages and ratios. Rate of B is 60% more than rate of A which means that rate of B is 8/5 the rate of A. So ratio of their rates is 8:5. Then ratio of time taken by B:A will be 5:8. Since A takes 12 days, 8 on ratio scale is equal to 12 actually so multiplier is 12/8 = 3/2. Time. taken by B will be 5 * 3/2 = 7.5 days Answer (D) Check the following videos for more on Ratios: https://youtu.be/5ODENGG5dvc Percentages: https://youtu.be/HxnsYI1Rws8

bumpbot · Answer

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A can complete a certain job in 12 days. B is 60% more efficient than

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