SSC Sample Paper Mock Test-19 SSC CGL Tear-II Paper-1

A can do a piece of work in 60 days. He works for 15 days and then B alone finishes the remaining work in 30 days. The two together can finish the work in

A) 24 days

B) 25 days

C) 30 days

D) 32 days

Correct Answer: A

Solution :

Work done by A in 15 days\[=\frac{1}{60}\times 15=\frac{1}{4}\]

Remaining work \[=\left( 1-\frac{1}{4} \right)=\frac{3}{4}\]

Now, \[\frac{3}{4}\]work is done by B in 30 days.

\[\therefore \] Whole work will be done by B in

\[\frac{30\times 4}{3}=40\,\,\text{days}\]

\[\therefore \] A's 1 day's work \[=\frac{1}{60}\]

and B's 1 day's work \[=\frac{1}{40}\]

\[\therefore \] (A + B)'s 1 day's work

\[=\frac{1}{60}+\frac{1}{40}=\frac{2+3}{120}=\frac{5}{120}=\frac{1}{24}\]

Hence, both will finish the work in 24 days.