Five drainage pipes, each draining water from a pool at the same constant rate, together can drain a certain pool in 12 days. How many additional pipes, each draining water at the same constant rate, will be needed to drain the pool in 5 days?
Choose the correct choice from the following choices
A) 6
B) 7
C) 10
D) 12
E) 15
This is an inverse proportional problem......   5 pipes in 12 days; So for 4 days, it will be = 12 x 5 / 5 = 12   So, 12-5 = 7   Answer 7
<result>B</result>
Five drainage pipes, each draining water from a pool at the same constant rate, together can drain a certain pool in 12 days. How many additional pipes, each draining water at the same constant rate, will be needed to drain the pool in 5 days?