RRB RPF RPSF SI and CONS Model Papers 2 with solutions

(c) 10 men in 15 days
⇒ 1 man can do the work in 150 days
⇒ 1 man can do twice the work in 300 days
Similarly, 18 boys in 15 days
⇒ 1 boy can do the work in 270 days
⇒ 1 boy can do twice the work in 540 days
Now, if there are 15 men and 33 boys trying to do twice the work then $\left(15\times \frac{1}{300}\right)+\left(33\times \frac{1}{540}\right)$ $=\frac{1}{20}+\frac{11}{180}=\frac{9+11}{180}$ $=\frac{20}{180}=\frac{1}{9}$
⇒ It will take 9 days for 15 men and 33 Boys to do twice the work.