A cylindrical vessel open at the top has diameter 20 cm and height 14

1.	A cylindrical vessel open at the top has diameter 20 cm and height 14 cm. Find the cost of tin-plating it on the inside at the rate of 50 paise per hundred square centimetre.
Answer» We have, Diameter of base of cylinder = 20 cm Radius of cylinder = 20/2 = 10cm Height of cylinder = 14 cm Total surface area of cylinder = 2πrh + πr² = (2 × 22/7 × 10 × 14) + (22/7 × 10²) = 880 + 2200/7 = (6160+2200)/7 = 8360/7 cm² We know that cost per 100cm² = 50paise So, cost per 1cm² = Rs 0.005 ∴ Cost of tin painting the area inside the vessel = 8360/7 × 0.005 = Rs 5.97

A cylindrical vessel open at the top has diameter 20 cm and height 14 cm. Find the cost of tin-plating it on the inside at the rate of 50 paise per hundred square centimetre.

Answer»

We have,

Diameter of base of cylinder = 20 cm

Radius of cylinder = 20/2 = 10cm

Height of cylinder = 14 cm

Total surface area of cylinder = 2πrh + πr²

= (2 × 22/7 × 10 × 14) + (22/7 × 10²)

= 880 + 2200/7

= (6160+2200)/7

= 8360/7 cm²

We know that cost per 100cm² = 50paise

So, cost per 1cm² = Rs 0.005

∴ Cost of tin painting the area inside the vessel = 8360/7 × 0.005

= Rs 5.97