The material needed to make the skin of a basketball costs $71.62 / m2. A standard basketball has a diameter of 24 cm. To the nearest dollar, how much does a basketball cost to make?
The formula for the surface area of a sphere is: Area = 4·pi·r2.
If the basketball has a diameter of 24 cm, its radius is 12 cm.
Area = 4·pi·r2 ---> Area = 4·pi·122 = 1809.56 sq cm.
If the cost is $71.62 per sq m, the cost, per square cm is $71.62 / 1002 = $ 0.007162.
Final cost: $ 0.007162 x 1809.56 = $12.96.