Question

a swimming pool has 3 drain pipes .the first two pipes a and b operating simultaneously can empty the pool in half the time than c,the 3rd pipe alone takes to empty it.pipe a working alone takes half the time taken by pipe b.together they take 6 hr 40min to empty the pool.time taken by pipe a to empty the pool is how much?

Answer 1

Answer:

Let efficiency of pipe B = x

Pipe A is twice as efficient as pipe B. Therefore, efficiency of pipe A = 2x

A and B together is twice as efficient as pipe C. Therefore, efficiency of pipe C   = 1/2(x+2x) = 3x / 2

A  : B  : C

2x : x : 3x/2 = 4 : 2 :3

All the pipes together empty the pool in 400 minutes. Therefore, Part of the tank emptied by all the pipes together in 1 minute

= 1 / 400

Part of the tank emptied by pipe A in 1 minute

=  1 / 400 * 1 / 4+2+3 = 1 / 900

i.e., pipe A alone needs 900 minutes (15 hours) to empty the pool.