A large 39 ounce can of Campbells soup requires 1885 square

A large 39 ounce can of Campbell\'s soup requires 188.5 square inches of aluminum to make. If its height and 7 inches what is the radius of the can? round the answer to the nearest decimal places

Solution

Total Surface Area of can in the form cylinder (S)= pi*r*h +2*pi*r^2

Given : S = 188.5 sqinches ; h = 7 inches

7pi*r +2pi*r^2 = 188.5

Divide equation by pi:

7r +2r^2 = 60

2r^2 + 7r -60 =0

Solving the quadratic equation by using quadratic root formula: r = ( -7 +/- sqrt(49+4*60*2) )/4

r = 4 inches , -7.5 inches. Neglecting -ve value.

So, radius = 4 inches