Practice | Hashtable

Home > Practice > Arithmetic Aptitude > Chain Rule > Miscellaneous

1. 49 pumps can empty a reservoir in $6 \frac{1}{2}$ days, working 8 hours a day. If 196 pumps are used for 5 hours each day, then the same work will be complete in ?

A. 2 days

B. $2 \frac{1}{2}$ days

C. $2 \frac{3}{5}$ days

D. 3 days

Solution:

Let the required number of days be x
Then,
More pumps, Less days (Indirect proportion)
Less working hour/day, More days (Indirect proportion)

\begin{matrix} Pumps 196 : 49 \\ Working hour/day   5 : 8 \end{matrix}} :: \frac{13}{2} : x

\begin{aligned} ∴ 196 \times 5 \times x = 49 \times 8 \times \frac{13}{2} \\ \Leftrightarrow x = (49 \times 8 \times \frac{13}{2} \times \frac{1}{196 \times 5}) \\ \Leftrightarrow x = \frac{13}{5} \\ \Leftrightarrow x = 2 \frac{3}{5} \end{aligned}

You must login to add comments. Login now.