Ratio of their linear expansion = ^∝₁/_∝[sub]2[/sub]= 3:4.
When heated to the same temperature range, the ratio of their increase in length ^e₁/_e[sub]2[/sub] = 1:2
But the increase in length of
1 = e₁ = ∝₁l₁Δθ and increase i length of
2 = e₂ = ∝₂l₂Δθ=> e₁ = ∝₁l₁Δθ = ∝₁l₁ = 1

e2	∝2l2Δθ	∝2l2	2

But ∝₁ = 3 , ∴ 3 x l₁= 1

∝2	4	4	l2	2

=> 6l₁ = 4l₂∴ l₁= 4 = 2 OR 2 : 3

l2	6	3