Question

50 two rupees coins are place one above the other to form a right circular cylinder if each coin has radius 1.4 cm and thickness is 0.3 cm find it total surface area

Answer 1

we have,
thickness of a coin = 0.3 cm
thickness of 50 coins = 50 × 0.3 = 15 cm
radius of a coin = 1.4 cm
now since the coins are placed one above the other to form a right circular cylinder
radius(r) of base of the cylinder = 1.4 cm
and height(h) of cylinder = thickness of 50 coins = 15 cm

Total surface area of cylinder = 2×pi×r (r+h)
= 2 × (22/7) × 1.4 (1.4 + 50)
= (44/7) × 1.4 × 51.4
=> 8.8 × 51.4
= 452.32 cm^2