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

Explanation

Diameter of base of cylinder = `20 cm`
Radius of cylinder =` 20/2`
`10cm `
Height of cylinder =` 14 cm`
Total surface area of cylinder =` 2pirh + pir^2 = (2 xx22/7 xx 10 xx 14) + (22/7 xx10^2) `
`= 880 + 2200/7 `
` (6160+2200)/7 = 8360/7 cm2`
We know that cost per `100cm^2 = 50paise`
So, cost per `1cm2 = Rs 0.005`
Cost of tin painting the area inside the vessel
`8360/7 xx 0.005 = Rs 5.97`