Dimensional changes

Question

The radius of a circle whose area is 144π ft2 is reduced by a factor of 6. What is the exact area of the new circle?

Answer 1

Area = pir^2 = 144pi

r^2 = 144

r = 12

reduce r by factor of 6 means new r = 12/6 = 2

Area = pi(2)^2 = 4pi

144pi/4pi = 144/4 = 36

Area decreases by a factor of 6^2 = 36

new circle has area of 4pi square feet