Question

An oil tanker can be emptied by the main pump in 4 hours. An auxiliary pump can empty the tanker in 9 hours.If the main pump is started at 6 PM, when should the auxiliary pump be started so that the tanker is emptied by 9 PM,The auxiliary pump should be started at

Answer 1

Step-by-step explanation

To solve the question, we will be aware that

There are 3 hours between 6PM and 9PM ,

The main pump's emptying rate is 1/4 tanker per hour. It will be open

the entire 3 hours, so it will empty 3/4 of the tank.

this means that the auxiliary pump must empty the remaining 1/4

Thus

`rate\text{ in tanker per hour }* time\text{ required=}(1)/(4)tank`

Thus, we will have

`(1)/(4)*3\text{ hours =45 minutes}`

Therefore

The auxiliary pump should start by 6pm + 45 minutes = 6:45pm