Question

Pipes M and N can empty the tank in 21 minutes and 28 minutes respectively. They are opened alternately for one minute each, starting with N. The time taken to empty the tank is

Answer 1

Answer:

So when all 3 pipes work together, total inflow of water into the cistern per minute is 2+(8/9)+(1/2)=61/18 liters. Time needed to fill 122 liters = 122/(61/18) = (122*18)/61 = 2*18 = 36 minutes.

Explanation:

pls mark me as brainiest,like my answers and follow me