Question

2 taps A and B can fill a tank in 12 hours and 9 hours respectively. if both of them are opened together,how long will they take to fill the tank completly

Answer 1

Step-by-step explanation:

take LCM of 12 and 9 , that is 36

so total work is 36 unit

now

A can fill the tank in 12 hour hence work done by A is 36/12 unit = 3 unit

and B can fill the tank in 9 hour , hence work done by B is 36/9 = 4 unit

if A and B opened together then work done is 3+4 unit

= 7 unit

now time required to complete 36 unit work = 36 / 7

= 5 + 1/7 hours