Answer:
The radius has an increase of 41.4%
Explanation:
We have that the surface area formula is equal to:
a = 4 * pi * r ^ 2
in this case if you assume an area of 100 and we calculate the radius it would be:
100 = 4 * pi * r ^ 2
we solve for r:
r ^ 2 = 100/4 * pi
r ^ 2 = 100 / (4 * 3.14)
r ^ 2 = 7.9617
r = 2,822
now if we double the area, that is 200:
r ^ 2 = 200 / (4 * 3.14)
r ^ 2 = 15.9236
r = 3,990
So the change of the radius would be:
3.99 / 2,822 = 1,414
That is to say that the radius has an increase of 41.4%