Problem Solving

Hi All,

We're told that Max can complete a job in 4 hours and Nick can complete the same job in 6 hours. We're asked how many FEWER hours it would take Max and Nick working together to complete the job than Max alone needs to complete the job. This question can be solved in a couple of different ways, including with the Work Formula.

Work = (A)(B)/(A+B) where A and B are the two times the individuals take to complete the job alone.

With Max's time of 4 hours and Nick's time of 6 hours, working together, it would take them...

(4)(6)/(4+6) = 24/10 = 2.4 hours to complete the job

The difference between Max's time and 'combined' time is 4 - 2.4 = 1.6 hours.

Final Answer: A

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorLU wrote:Source: Princeton Review

If Max can complete a job in 4 hours and Nick can complete the same job in 6 hours, how many fewer hours do Max and Nick working together need to complete the job than Max alone needs to complete the job?

A. 1.6
B. 2.4
C. 3.2
D. 3.4
E. 5.0

The combined rate for Max and Nick is:

1/4 + 1/6 = 3/12 + 2/12 = 5/12, so the time needed to completed the job together is 12/5 = 2.4 hours.

So it takes 4 - 2.4 = 1.6 hours less when they complete the job together than if Max were to complete the job alone.

Answer: A