A) 50 min
B) 12 min
C) 25 min
D) 15 min
Correct Answer: B
Solution :
Required time\[=\frac{1}{\begin{matrix} 1 \\ 20 \\ \end{matrix}+\begin{matrix} 1 \\ 30 \\ \end{matrix}}=\frac{20\times 30}{50}=12\min \]You need to login to perform this action.
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