Question

The diameter of a sphere is multiplied by 1/5. What is the effect on the surface area?

Answer choices:

5 times bigger
5 times smaller
25 times bigger
25 times smaller
15 times bigger
15 times smaller
125 times bigger
125 times smaller
Answer is not here

Answer 1

We know the ratio of sides to area

• a/b=a²/b²

So

If diameter is multiplied by 1/5

Surface are increases

• (1/5)²
• 1/25

25 times smaller

Answer 2

• 25 times smaller

Explanation:

Scale factor is:

• k = 1/5

Ratio of surface areas is:

• k² = (1/5)² = 1/25

Surface area will be 25 times smaller

Correct choice is D