Question

Two pipes a and b can fill a tank in 6 hours and 8 hours respectively.Both the pipes are opened together, but 2.5 hour after the start, the pipe B is turned off .How much time it take to fill the tank?

Answer 1

13/8 hr is the right answer...

Answer 2

Answer:

The total time (in hours) taken to fill the tank completely is 4 hours.

Step-by-step explanation:

Given:

Pipe A can fill a tank in 6 hours

Pipe B can fill a tank in 8 hours

Pipe $\mathrm{C}$ alone can empty the full tank in 12 hours.

$A and B$ are opened together for 2 hours and then $C$  is also opened

Formula used:

Time taken by $A+B+C= Remaining work/Efficiecy.$$(A+B+C)$

Calculation:

According to the question;

$A and B$are opened together for 2 hours,

$\begin{aligned}&2(A+B) \\&\Rightarrow 2 \times(4+3)=14 \text { work }\end{aligned}$

Left work $=24-14=10$ work

Total time taken by $A+B+C=10 /(a+b+c) \\efficiency \Rightarrow 10 /(4+3-2)\\=10 / 5=2$hours

Now,

Total time $=(2+2) hours =4 hours$

$\therefore$ The total time (in hours) taken to fill the tank completely is 4 hours.