A pipe of radious 1 cm can fill up a tank in 20 minut ;time to taken by another pipe of radious 2 cm to fill ;it will be
basic assumption:
time of filling is inversely proportional to the square of the radius
1^2/2^2 = t/20
4t = 20
t = 5
time of filling is inversely proportional to the square of the radius
1^2/2^2 = t/20
4t = 20
t = 5