Time and Work - Solved Examples

Posted on - 13-02-2017

Bank PO

Example.1

A hostel has provision for 800 men tor 24 days at rate of 2 kg per man per day. For how many men is the provisions sufficient, for 20 days at the rate of 1 x 5 kg per man per day? .

Solution

Total food available = (800 x 24 x 2) kg

Let the number of men be x

So 800 x 24 x 2 = x x 20 x 1 x 5

x = = 1280

The food is sufficient for 1280 men. .

example.2

Two pipes can fill a tank in 15 minutes and 25 minutes respectively. Both pipes are opened together and after some time the first pipe is closed and the tank is filled in a total of 15 minutes. For how many minutes is the first pipe open? .

Solution

Second pipe is opened for 15 minutes. So, part of tank filled by the second pipe =

So is filled by first pipe. First pipe can fill of tank in x 15 = 6 minutes. So the first pipe is opened for 6 minutes.

example.3

Pipe A can fill a tank in 8 hours and pipe B can empty the full tank in 15 hours. If the both pipes are opened together, in how much time will the tank become full? .

Solution

Part of tank filled by pipe A in 1 hour r =

Part of the tank that can be emptied by B in 1 hour = . When both pipes are opened the part of the tank filled in 1 hour

So the tank will become full in = hours.

example.4

12 men can do a work in 15 days working 8 hours a day. In how many days can 9 men do the same work, working 10 hours a day? .

Solution

We have M₁D₁H₁ = M₂D₂H₂

So 12 x 15 x 8 = 9 x D₂ X 10

D₂= 16 days. .

example.5

Due to a leak at the bottom, pipe Y takes 15 hrs to fill the tank and the leak alone can empty the full tank in 10 hrs. In what time can pipe Y alone fill the tank when the leak is closed? .

Solution

Let pipe Y takes x hrs to fill the tank when the leak is closed. .

Due to the leak Y takes 15 hrs to fill the tank. .

Leak alone can empty the fill tank in 10 hrs. .

&⇒

&⇒ x = 6 hrs.