question_answer

Four taps can individually fill a cistern of water in 1 hour, 2 hours, 3 hours and 6 hours respectively. If all the four taps are opened simultaneously, the cistern can be filled in how many minutes?

A) 20 minute                     

B) 30 minute

C) 35 minute                     

D) 40 minute

Correct Answer: B

Solution :

Time required \[=\frac{6}{6+3+2+1}hrs.\] \[=\frac{6}{12}\times 60\] minutes = 30 minutes