Answer to GMAT Question #14

Here is the answer to GMAT Practice Question #14

Answer: B

Explanation:
The question tells us that the three machines can print 100,000 copies of a flier in 40 hours. This defines the job as 100,000 fliers. Thus, figuring out how long it will take to complete 200,000 isn’t too hard – it’s just two jobs and so we can work it out assuming 100,000 and multiply by 2. Plugging into the work problem formula:

40/a + 40/b + 40/c = 1

Statement one tells us that a and c, when working together, take 48 hours. So we can make a work formula just for this statement:

48/a + 48/c = 1 This is a great opportunity for substitution into the first equation. Since in that equation, 40 is in the numerator of each fraction, we should adjust this one to fit by multiplying everything by 5/6:

40/a + 40/c = 5/6

Plugging in: 5/6 + 40/b = 1

Thus, you can solve for b but not forc. So this is not enough information.

We can apply the same logic to statement 2: 120/a + 120/b = 2

Now, multiply through by 1/3 to bring the numerators to 40: 40/a + 40/a = 2/3

Plug in: 2/3 + 40/c = 1

Now, we can solve for c.

Thus, the answer is B.

The answer and explanation to GMAT Practice Question #14 was written by Integrated Learning, a company that provides professional and private one on one tutoring services.