How many coins 1.75 cm in diameter and 2 mm thick must be melted to fo

1.	How many coins 1.75 cm in diameter and 2 mm thick must be melted to form a cuboid 11 cm x 10 cm x 7 cm?
Answer» Given, Diameter of the coin = 1.75 cm So, its radius = 1.74/2 = 0.875 cm Thickness or the height = 2 mm = 0.2 cm We know that, Volume of the cylinder (V₁) = πr²h = π 0.875² × 0.2 And, the volume of the cuboid (V₂) = 11 × 10 × 7 cm³ Let the number of coins needed to be melted be n. So, we have V₂ = V₁ × n 11 × 10 × 7 = π 0.875² × 0.2 x n 11 × 10 × 7 = 22/7 x 0.875² × 0.2 x n On solving we get, n = 1600 Therefore, the number of coins required are 1600.

How many coins 1.75 cm in diameter and 2 mm thick must be melted to form a cuboid 11 cm x 10 cm x 7 cm?

Answer»

Given,

Diameter of the coin = 1.75 cm

So, its radius = 1.74/2 = 0.875 cm

Thickness or the height = 2 mm = 0.2 cm

We know that,

Volume of the cylinder (V₁) = πr²h

= π 0.875² × 0.2

And, the volume of the cuboid (V₂) = 11 × 10 × 7 cm³

Let the number of coins needed to be melted be n.

So, we have

V₂ = V₁ × n

11 × 10 × 7 = π 0.875² × 0.2 x n

11 × 10 × 7 = 22/7 x 0.875² × 0.2 x n

On solving we get, n = 1600

Therefore, the number of coins required are 1600.