domu904
A small water pump would take 2 hours to fill an empty tank. A larger pump would take 1/2 hour to fill the same tank. How many hours would it take both pumps, working at their respective constant rates, to fill the empty tank if they began pumping at the same time?
A) 1/4
B) 1/3
C) 2/5
D) 5/4
E) 3/2
Given:
1. A small water pump would take 2 hours to fill an empty tank.
2. A larger pump would take 1/2 hour to fill the same tank.
Asked: How many hours would it take both pumps, working at their respective constant rates, to fill the empty tank if they began pumping at the same time?
1. A small water pump would take 2 hours to fill an empty tank.
In 1 hour, small water pump will fill = 1/2 of tank
2. A larger pump would take 1/2 hour to fill the same tank.
In 1 hour, small water pump will fill = 2 of tank
Working together, in 1 hour small & large pump will fill = 2.5 of tank
Number of hours required to fill the empty tank together = 1/2.5 = 2/5 hours
IMO C