surface area of smaller = 4π r^2
surface area of larger = 4π(3r)^2 = 36πr^2
which is 9 times as great
or
the area of similar objects is proportional to the square of their linear dimension,
so 1^2 : 3^2
= 1 : 9
The diameter of a sphere is three times that of another sphere.How many times greater is its surface area
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