Two pipes A and B can fill a tank in 20 and 30 minutes respectively . If both the pipes are used together , then how long will it take to fill the tank ?

A 12 min
B 15 min
C 25 min
D 50 min

Correct Answer: 12 min

A pipe fill 1/20 portion of tank in 1 min B pipe fill 1/30 portion of tank in 1 min So, together pipe fill ( 1/20 + 1/30) portion of tank in 1 min = ( 3 + 2) / 60 = 1/12 Now, they fill 1/12 portion in 1 mint So, they fill 1 (whole) portion in ( 1×12)/1 = 12 minutes
Bissoy MCQ
#গণিত #Bangladesh Bank #নল ও চৌবাচ্চা (Pipes and cistern) #Bangladesh Bank - Assistant Director - 2014

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