Indian Institute of Foreign Trade 2011 Solved Paper

It is given that a man is able to perform the work equal to the same done by 2 boys. Hence, we can assume that In Bilaspur village 21=(12+18/2) men completed construction of a primary health center in 60 days, by working for 7.5 hours a day.Hence, total men hours required to completed the primary health center in Bilaspur $=7.5 \times 21 \times 60 = 9450.$Let us assume that 'n' be the number of boys required to help 21 men to complete the work in Harigarh in 50 days by working 9 hours a day.Therefore, we can say that$\Rightarrow 2 \times 9450 = 50 \times 9 \times \left(21 + \frac{t}{2}\right)$$\Rightarrow 42 = 21 + \frac{t}{2}$$\Rightarrow t = 42$Hence, option D is the correct answer.