Question

Two pipes A and B can fill a tank in 6 minutes and 7 minutes respectively. Both the pipes are opened alternately for a minute each, find in how much time they will fill the tank?
(a) 5 minutes
(b) 5 2/3 minutes
(c) 6 3/7 minutes
(d) 1 1/4minute​

Answer 1

Answer:

c

Step-by-step explanation:

As the pipes are operating alternatively, thus their 2 minutes job is = 1/6 + 1/7 = 13/42

In the every 2 minutes the pipes can fill another 13/42 part of cistern.

Therefore, In 6 minutes the two pipes which are operating alternatively will fill

13/42 + 13/42 + 13/42 = 13/14

Remaining part = 1 - 13/14 = 1/14

Pipe A can fill 1/6 of the cistern in 1 minute

Pipe A can fill 1/14 of the cistern in = 6/14 = 3/7 min

Therefore, Total time taken to fill the Cistern 6 + 3/7 min