#### Question

How many coins 1.75cm in diameter and 2mm thick must be melted to form a cuboid 11cm x 10cm x 75cm___?

#### Solution

Given that dimensions of a cuboid 11cm x 10cm x 75cm

So its volume (V_{1}) = 11cm x 10cm x 7cm

= 11 x 10 x 7cm^{3} ..........(1)

Given diameter (d) = 1.75cm

Radius (r)`=d/2=1.75/2=0.875cm`

Thickness (h) =2mm = 0.2cm

Volume of acylinder =`pir^2h`

`V_2=pi(0.875)^2(0.2)cm^3` ........(2)

V_{1} = V_{2} x n

Since volume of a cuboid is equal to sum of n volume of ‘n’ coins

`n =V_1/V_2`

n = no of coins

`n=(11xx10xx7)/(n(0.875)^2(0.2))_`

n = 1600

∴No of coins (n) = 1600

Is there an error in this question or solution?

Solution How Many Coins 1.75cm in Diameter and 2mm Thick Must Be Melted to Form a Cuboid 11cm X 10cm X 75cm___? Concept: Volume of a Combination of Solids.