Question

A water tank has 3 inlets. Inlet A alone can fill the tank in 30 minutes. Inlet B can fill it in 40 minutes Inlet C can fill it in 60 minutes. If all the 3 inlets are opened together, how long will it take to fill the tank?

Answer 1

1/30+1/40+1/60
4/120+3/120+2/120
9/120
120/9 minutes= 40/3 minutes

Answer 2

Answer:

13.3 minutes

Step-by-step explanation:

A alone can fill the tank in 30 minutes.

A's 1 hour work = $\frac{1}{30}$

B can fill it in 40 minutes

B's 1 hour work = $\frac{1}{40}$

C can fill it in 60 minutes.

C's 1 hour work = $\frac{1}{60}$

They work together in 1 hour = $\frac{1}{30}+\frac{1}{40}+\frac{1}{60}$

                                                 = $\frac{3}{40}$  

If they work together it will take time to fill the tank= $\frac{40}{3}=13.33$  

Hence it will take 13.3 minutes to fill the tank if they work together