The formula for the surface of a sphere is \(S=4πr^2\). Two lead balls have radii 3 inches and 6 inches, respectively. A third ball has surface area equal to the sum of the surface areas of the two smaller balls. What is the radius, in inches, of the third ball?
(A) \(3\sqrt{10}\)
(B) \(3\sqrt{5}\)
(C) \(36π\)
(D) \(45π\)
(E) \(180π\)
It's not really a hard question, but I got it wrong because I didn't take enough time to read carefully the question. So i'll just leave it here for others to avoid my mistake.
Good luck ya'll
PS: Difficulty is probably under 600, but couldn't edit the tags