Question

How many silver coins, 1.75 cm in diameter and of thickness 2mm, must be melted to form cuboid of dimension 5.5cm x 10cmx 3.5cm?​

Answer 1

Step-by-step explanation:

volume of coin × number of coins = volume of cuboid

coin is in the shape of cylinder

let the number of coins be x

$x \times \pi {r}^{2} h = l \times b \times h \\ x \times \frac{22}{7} \times 0.85 \times 0.85 \times 0.2 = 5.5 \times 10 \times 3.5 \\ x = \frac{5.5 \times 10 \times 3.5 \times 7}{0.85 \times 0.85 \times 0.2 \times 22} \\ x = \frac{55 \times 3.5 \times 7}{0.85 \times 0.85 \times 0.2 \times 22} \\ x = \frac{5 \times 24.5}{0.85 \times 0.85 \times 0.4} \\ x = \frac{122.5}{0.289} \\ x = 423$

we require 423 coins to form a cuboid

hope you get your answer

Answer 2

We have,

Radius of coin = 1.75/2 = 00.875 cm

Thickness, i.e, height = 2/10 = 0.2 cm

The shape of the coin will be like the shape of cylinder

Volume of the coin = πr²h

Volume of the coin = 22/7 × 0.875 × 0.875 × 0.2

Now, Volume of the cuboid = 5.5 × 10 × 3.5

Therefore, Number of coins required to form a cuboid = Volume of the cuboid/Volume of the coin

Number of coins required to form a cuboid = 5.5 × 10 × 3.5/22/7 × 0.875 × 0.875 × 0.2

Number of coins required to form a cuboid = 400

Hence, There are 400 silver coins melted to form a cuboid.