Pipe A and Q can fill a tank in 15 hrs and 20 hrs respectively. Pipe A is opened for two third of the time and then both pipes are opened for the remaining time. How long will it take to fill the tank?
Answer & explanation
Correct answer: option 3
ATQ,
Let total time taken to fill the tank is 't' hours.
Then,
⇒ [4 × \(\frac{2t}{3}\)] + [7 × \(\frac{t}{3}\)] = 60
⇒ [\(\frac{8}{3}\) + \(\frac{7}{3}\)] t = 60
⇒ 5 t = 60
⇒ t = \(\frac{60}{5}\) = 12 hrs.