A pipe can empty a tank in 16 min. A second outlet pipe with diameter twice as much as that of the first is also attached with the tank. Working together how much time will be taken by both pipes to empty the tank.

\(\frac{16}{3}\) min

Note: Ratio of efficiency of the pipes is always equal to the square of the radius of the pipes.

                     I     :     II

Diameter :    D    :    2D

Radius    :    1     :     2

Efficiency:    1²   :     2²

Time       :    4     :     1

Here,

4R = 16 min,

1R = 4 min.

Total time taken by both the pipes = \(\frac{16}{4-1}\) =  \(\frac{16}{3}\) mins.