# Pipe A can fill a tank in 12 hours and Pipe B can fill the tank in 18

| Pipe A can fill a tank in 12 hours and Pipe B can fill the tank in 18 hours. If both the pipes are opened on alternate hours and if pipe B is opened first, then in how much time (in hours) the tank will be full?

A.

B.

C.

D.

### Right Answer is: C

#### SOLUTION

let capacity of tank be 72litre (since it is a multiple of both 12 and 18)

Then efficiency of pipe A=72/12=6

Efficiency of pipe B=72/18=4

Pipes are opened alternatively and pipe B is opened first,, then the water filled in two hour

= water filled by pipe A+ water filled by pipe B = 6+4=10 litre

10 litre in 2 hour

70 litre=

Remaining volume =72-70=2

Now it’s B turn to fill the tank , as it started the fist, so time taken=

So total time taken=14+1/2=

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Pipe A can fill a tank in 12 hours and Pipe B can fill the tank in 18