. One pump can fill a tank with oil in 4 hours. A second pump can fill the same tank in 3 hours. If
both pumps are used at the same time, about how long will they take to fill the tank? Round to
the nearest tenth.
a. About 2.1 hours
b. About 1.7 hours
c. About 7 hours
d. About 3.5 hours
To calculate the combined rate of the two pumps, we add their rates together.
Rate of first pump = 1 tank / 4 hours = 1/4 tank per hour
Rate of second pump = 1 tank / 3 hours = 1/3 tank per hour
Combined rate = 1/4 + 1/3 = 3/12 + 4/12 = 7/12 tank per hour
Therefore, the pumps will take approximately 12/7 hours to fill the tank together, which is about 1.7 hours.
So, the answer is:
b. About 1.7 hours