The ratio of the total surface area and volume of a sphere is 2 : 7. Its radius is:
Answer & explanation
Correct answer: option 2
We know that,
Total surface area of sphere = 4πr2
Volume of a sphere = \(\frac{4}{3}\) πr3
We have,
Ratio of total surface area and volume of a sphere = 2 ∶ 7
According to the question,
(4πr2) : (\(\frac{4}{3}\) πr3) = 2 : 7
= \(\frac{3}{r}\) = \(\frac{2}{7}\)
= r = 10.5cm