Question

4. Five taps can empty a tank in 3 hours. It is found that 2 taps are out of order (not
working) then, the remaining 3 taps will empty the tank in
a. 9 hrs
b. 8 hrs
C. 5 hrs
d. 6 hrs

Answer 1

Given :

Five taps can empty a tank in 3 hours

To Find :

Time taken by 3 taps to empty the tank

Solution :

•let the rate of suction of each tap be v litres / hour i.e. each tap can empty v litres of water in one hour

•So, Amount of water emptied by one tap in 3 hours is 3v litres

Now , Amount of water emptied by five taps in 3 hours will be 15v litres

•Therefore , Volume of tank is 15v litres ___________(1)

•Now , If 3 taps are working

let the time required is t

•so, Amount of water emptied by one tap in t hours is tv litres

Now , Amount of water emptied by three taps in 3 hours will be 3tv litres

•Therefore , Volume of tank is 3tv litres _________(2)

•From (1) & (2)

15v = 3tv

t = 5

•Hence , Time taken by three taps to empty tank is 5 hours