Acistern is filled in 5 hours and it takes 6 hours when thereis a leak in its bottom. If the cistern is full, in what time shall the leak empty it?
Let capacity of cistern = L.C.M. (5,6) = 30 units
Efficiency to fill it = $$\frac{30}{5}=6$$ units/hr
Let efficiency of leak = $$-x$$ units/hr
According to ques, => $$(6-x)\times6=30$$
=> $$6-x=5$$
=> $$x=1$$
$$\therefore$$ Time taken by leak to empty it = $$\frac{30}{1}=30$$ hours
=> Ans - (C)
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