The ratio of the total surface area and volume of a sphere is 2 : 7. Its radius is:

7.5 cm 10.5 cm 10 cm 7 cm

10.5 cm

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