question_answer

10 men working 6 h a day can complete a work in 18 days. How many hours a day must 15 men work to complete the same work in 12 days?  

A)       6

B)  10             

C)  12

D)  15   

Correct Answer: A

Solution :

\[\therefore \]      \[\left. \begin{align}   & 15:10 \\  & 12:18 \\ \end{align} \right\}:\,\,:6:x\] \[\Rightarrow \]   \[15\times 12\times x=10\times 18\times 6\] \[\Rightarrow \]   \[x=\frac{10\times 18\times 6}{15\times 12}=6\]