Question

one pump can empty a pool in 2 days, whereas a second pump can empty the pool in 11 days. How long will it take the two pumps, working together, to empty the pool?It will take the two pumps ___ days to empty the pool together.

Answer 1

Let x be the number of days it will take the two pump to empty the pool together

$(\frac{1}{2}+\frac{1}{11})\times x=1$$(\frac{11+2}{22})\times x=1$$\frac{13}{22}x=1$

Multiply both-side by 22/13

$x=\frac{22}{13}$$=1.6923$