#### Question

How many silver coins, 1.75 cm in diameter and of thickness 2 mm, must be melted to form a cuboid of dimensions 5.5 cm × 10 cm × 3.5 cm? [Use π=22/7]

#### Solution

Coins are cylindrical in shape.

Height (*h*_{1}) of cylindrical coins = 2 mm = 0.2 cm

Radius (*r*) of circular end of coins = 1.75/2 =0.875 cm

Let *n* coins be melted to form the required cuboids.

Volume of *n* coins = Volume of cuboids

nxπxr^{2}xh_{1} = lxbxh

n x π x (0.875)^{2} x 0.2 = 5.5 x 10 x 3.5

`n = (5.5xx10xx3.5xx7)/((0.875)^2xx0.2xx22) = 400`

Therefore, the number of coins melted to form such a cuboid is 400.

Is there an error in this question or solution?

Solution How many silver coins, 1.75 cm in diameter and of thickness 2 mm, must be melted to form a cuboid of dimensions 5.5 cm × 10 cm × 3.5 cm? Concept: Conversion of Solid from One Shape to Another.