Question 47
A sphere is cut into two equal halves and both the halves are painted.The radius of the sphere is 4 units and the rate of painting is ₹12 per sq. unit.What is the total cost (in ₹, rounded)?(Take π = 22/7)
Solution
A sphere is cut into 2 hemispheres.
Surface are of a hemisphere = $$3\pi\ r^2$$.
Surface area of 2 hemispheres with radius 4 units is $$2\times\ 3\pi\ 4^2\ =\ 96\pi\ $$ sq. units.
Cost of painting = $$96\pi\ \times\ 12=1152\pi\ \approx\ 3620.57$$ rupees.
