Question

(4)
A metal cuboid of measures 16 cm x 11 cm x 10 cm was melted
to make coins. How many coins were made, if the thickness and
diameter of each coin was 2 mm and 2 cm respectively ?​

Answer 1

Concept

As cuboid is melted to form a coins so the volume of of cuboid is equal to volume of all coins as coins are shape of cyclinder.

Solution

let the number of coins = n

Volume of cyclinder= πr2h

Volume of cuboid = l× b ×h

Volume of cuboid = volume of cyclinder × n

Length, breadth, height = (16× 11× 10)cm respectively.

Volume of cuboid = l× b ×h

Volume of cuboid= 1760cm^3

Height of cyclinder= 2mm =0.2cm

Radius of cyclinder= 1 cm

Volume of cyclinder= 22/7× 1×1×0.2 = 0.62cm^3

Volume of cuboid = volume of cyclinder × n

1760 = 0.62 × n

1760/0.628 = n

2802. 54 = n

Number of coins made are 2802.54 approx.

Answer 2

Answer:

2800 coins

Explanation:

Find the volume of the metal cuboid:

Volume = Length x Breadth x Height

Volume = 16 x 11 x 10

Volume = 1760 cm³

Find the volume of each coin:

*Note that 2 mm is equal to 0.2 cm

Volume = πr²h

Volume = π(2 ÷ 2)² (0.2)

Volume = 0.2π cm³

Find the number of coins:

Number of coins = 1760 ÷ 0.2π

Number of coins = 2800

Answer: 2800 coins