Question

the radius and height of closed cylindrical cistern are 50 cm and 90 cm respectively. find the cost of painting its total external surface at the rate if 4 per 100 cm square

Answer 1

Given,
Radius of cistern= 50 cm
Height of cistern= 90 cm
Cost of painting= ₹4/100 cm²
Now,
Total surface area= 2πr(h+r)
= 2*22/7*50(90+50)
= 2200/7*140
= 2200*20
= 44000 cm²
Now,
Cost of painting= 44000*4/100
= ₹ 1760

Hope this helps you!