Question

A pool can be filled with water by a large pipe within six hours .A smaller pipe will take 9 hours to fill the pool.How long will it take to fill the pool if the two pipes operate together

Answer 1

3.6 hours

Explanation:

The formula is

1/a+1/b = 1/c where a and b are the times working along and c is the time working together

1/6 + 1/9 = 1/c

Multiply by 36c to clear the fractions

36c (1/6 + 1/9 = 1/c)

6c +4c = 36

10c = 36

Divide by 10

10c/10 = 36/10

c = 3.6 hours working together