Question

youre in a rush and a single pump at the gas station is too slow. Pump A can fill your tank in 12 min. At what rate would pump B need to fill the tank alone if you must be done in 7 min with both pumps working concurrently.

Answer 1

bELOW

Explanation:

RATE A = 1 TANK / 12 MIN

RATE B = 1 TANK /? MIN

COMBINED : 1 TANK / (1 TANK/12 MIN + 1 TANK /? MIN) = 7 MIN

1 / ( 1/12 + 1/? ) = 7

1 = 7/12 + 7/?

5 /12 = 7/?

? = 7 * 12/5 = 16.8 MIN