A cistern is filled in 30 minutes by three pipes A, B and C. The pipe C is thrice as fast as pipe A and pipe B is twice as fast as A. The time taken by A alone to fill the cistern is :
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 180 minutes
Work Done per minute by A = $\frac{1}{x}$
Work done per minute by B = $\frac{2}{x}$
Work done per minute by C = $\frac{3}{x}$
$⇒\frac{1}{x}+\frac{2}{x}+\frac{3}{x}=\frac{1}{30}$
$⇒\frac{6}{x}=\frac{1}{30}$
$⇒x=180$ minutes