Very important question of mensuration including very important concept of it.
need solution!
Rd sharma class 10 maths exercise-16.1 mensuration.
we have to find number of coins of 1.75 cm in diameter and 2 mm thick which can be melted to form a cuboid 11 cm x 10 cm x 7 cm.
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