Two pipes can fill a tank in 10 h and 16 h respectively. A third
pipe can empty the tank in 32 h. If all the three pipes function
simultaneously, then in how much time the tank will be full? (in hours)

Options

A. `7 11/21`
B. `7 13/21`
C. `8 4/21`
D. `6 5/14`

Answer

(b)

Explanation

10 hr A pipe `rarr 1`
16 hr B pipe `rarr 1`
32 hr C pipe `rarr 1`
`1/10 + 1/16 - 1/32 = 21/160`
`160/21 = 7 13/21 `hr
Alternate Solution:

Working together in 1 hour, they fill-
`(16 +10 -5)` units = 21 units
`therefore` Total time required `= 160/21 = 7 13/21` hours.