Twice of radius

How many times does the surface of a sphere decrease if we reduce its radius twice?

Correct result:

n =  4

Solution:

S1=4 πr2 S2=4 π(r/2)2 S2=4 πr2/4=S1/4  n=S1/S2 n=4S_{1}=4 \ \pi r^2 \ \\ S_{2}=4 \ \pi (r/2)^2 \ \\ S_{2}=4 \ \pi r^2/4=S_{1} / 4 \ \\ \ \\ n=S_{1} / S_{2} \ \\ n=4



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