Practice | Hashtable

Home > Practice > Arithmetic Aptitude > Chain Rule > Miscellaneous

1. 3 pumps, working 8 hours a day, can empty a tank in 2 days. How many hours a day must 4 pumps work to empty the tank in 1 day?

A. 9

B. 10

C. 11

D. 12

Solution:

Let the required number of working hours per day be x.
More pumps, Less working hours per day (Indirect Proportion)
Less days, More working hours per day (Indirect Proportion)

\begin{matrix} Pumps  4 : 3 \\ Days 1 : 2 \end{matrix}} :: 8 : x

\begin{aligned} ∴ 4 \times 1 \times x = 3 \times 2 \times 8 \\ \Rightarrow x = \frac{3 \times 2 \times 8}{4} \\ \Rightarrow x = 12 \end{aligned}

You must login to add comments. Login now.