Water pump a, b and c could empty a pool for 6 hours, a and b pump could empty a pool for 8 hours how long (to the nearest minute) will it take to drain the pool if both pumps are used simultaneously?

3.4286 hours or 3 hours 26 minutes

Step-by-step explanation:

Well, it is considered that there are 5 different pumps (A, B, C, a and b). Pumps A and B are not same with pumps a and b.

Let us solve it. Well, it says a and b pump could empty a pool for 8 hours. So in 1 hour, pumps a and b empty 1/8 part of the pool.

And pumps A, B and C could empty a pool for 6 hours. Then A, B and C pumps empty 1/6 part of pool in 1 hour.

5 pumps (A, B, C, a and b) altogether can empty 7/24 parts (1/6+1/8=7/24) of a pool in 1 hour.

To drain whole pool, it will take 24/7=3.4286 hours or 3 hours 26 minutes.