Question

two pipes A&B can separately fill a cistern in 220 minutes and 330 minutes together they can fill the cistern in

Answer 1

A can fill cistern in 220min
B can fill cistern in 330min
Together means average time
=a+b/2
=220+330/2
=550/2
=225min

Answer 2

A can fill the cistern in 220min

⇒ 1 min = 1/220 of the cistern

B can fill the cistern in 330min

⇒ 1 min = 1/330 of the cistern

If A and B fill together

1 min = 1/220 + 1/330 = 1/132 of the cistern

Find the number of minutes needed:

1/132 of the cistern = 1 min

132/132 of the cistern = 1  x 132 = 132 min

Convert 132 mins to hours and mins:

132 mins = 2 hours and 12 mins

Answer: It will take 2 hours and 12 mins