Question

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

Answer 1

Assume silver coin to be a cylinder

Dimensions of silver coin
Height= 2 mm = 0.2 cm
Diameter= 1.75 cm
Radius= Diameter/2 = 1.75/2 = 0.875 cm

Dimensions of cuboid
Length= 5.5 cm
Breadth= 10 cm
Height = 3.5 cm

Volume of one silver coin
= pi *(r^2)*h
= 3.141(0.875)(0.875)(0.2)
= 0.481 cm^3

Volume of cuboid
= l * b * h
= 5.5(10)(3.5)
= 192.5 cm^3

No. of coins required to form cuboid
= Volume of cuboid/Volume of one coin
= 192.5/0.481
= 400.207
= 401 (rounded to next nearest number)

The answer is 401
Hope it helps.
(As Midhunmadhu1987 answered)

Answer 2

Answer:

Step-by-step explanation:

Solution :-

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.