the surface was 4 pi r^2 = 36pi
Now, replace r with (3/2) r and the new surface area is
4pi(3/2 r)^2 = 4pi * 9/4 r^2
= 4pi r^2 (9/4)
= 36pi(9/4)
= 81pi
Or, you could just solve for r and get that r increased from 3 to 9/2, so the area increased from 36pi to 81pi.
A spherical balloon with a surface area of 36pi square inches is inflated further until its diameter has increased by 50%. The surface area of the balloon is now? I know the formula for surface area is
A=4pi*r squared. I don't understand how you can figure the problem without knowing what the radius is? I thought you might take half of 36 and add the answer to 36 giving me 54pi square inches.
2 answers
The surface area is proportional to the square of their radii
(1.5r)^2/r^2 = x/36π
2.25/1 = x/36π
x = 2.2(36π) = 81π
(1.5r)^2/r^2 = x/36π
2.25/1 = x/36π
x = 2.2(36π) = 81π
1 answer