A water tap fills a tub in 'P' hours, and a sink at the bottom empties it in 'q' hours. If P < q and both taps are opened, the tank is filled in 'r' hours. The relation between P, q and r is?
Answer & explanation
Correct answer: option 2
Let the capacity of tank = pq ltr
then,
ATQ,Working together,
Tank will fill in (r hrs.) = \(\frac{pq}{q-p}\)
\(\frac{1}{r}\) = \(\frac{1}{p}\) - \(\frac{1}{q}\)