A pipe of diameter d can drain a certain water tank in 40

A pipe of diameter d can drain a certain water tank in 40 minutes. The time taken by a pipe of diameter 2d for doing the same job in :

As we know that ,

Time α	1
	cross sectional area of the pipe

Time α	1
	d²

∴	t₂	=	(d₁)²
	t₁		(d₂)²

[Being inversely related]

t₂ = t₁		d₁		²
		d₂

t₁ = 40 minutes, d₁ = d, d₂ = 2d

∴t₂ = 40		d		²
		2d

t₂ = 40		1		²
		2

Hence , t₂ = 10 minutes