Question

Mark the correct alternative in the following question:

If $\frac{4}{5}$ of a water tank is filled in 1 hour, then how much time will be required to fill the rest of it?

(a) 20 minutes (b) 15 minutes (c) 12 minutes (d) 10 minutes

Answer 1

As, the time taken to fill $\frac{4}{5}$ of the water tank = 1 hr = 60 min

⇒ The time taken to fill the water tank = 60 × $\frac{5}{4}$ = 15 × 5 = 75 min

So, the time required to fill the rest of the water tank = 75 − 60 = 15 min

Hence, the correct alternative is option (b).