Question

You are holding a spherical ball of radius 3.5 cm in your fist. You observe that 30% of area is uncovered. Then find the area of the ball uncovered. (Take $\pi =\frac{22}{7}$)

• A. $46.2{\text{cm}}^2$
• B. $26.2{\text{cm}}^2$
• C. $36.2{\text{cm}}^2$
• D. $16.2{\text{cm}}^2$

Answer 1

The correct option is A $46.2{\text{cm}}^2$

Given, Solid: Sphere
Radius of Sphere $r=2.5\text{cm}$
Area uncovered = 30%

The total surface area of the sphere gets covered when you hold the ball in fist.

Total surface area of ball$=4\pi r^2=4\times \frac{22}{7}\times 3.5\times 3.5=4\times 22\times 0.5\times 3.5=154{\text{cm}}^2$

30% of the area will be given by
Area uncovered $=\frac{30}{100}\times 154=46.2{\text{cm}}^2$