Question:medium

Find the volume of a sphere whose surface area is 154 cm2.

Updated On: Jan 19, 2026
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Solution and Explanation

Step 1: Surface Area of the Sphere

The formula for the surface area \( S \) of a sphere is:

\[ S = 4 \pi r^2 \] where \( r \) is the radius of the sphere. Given that the surface area \( S = 154 \, \text{cm}^2 \), we substitute this into the equation: \[ 154 = 4 \pi r^2 \]

Step 2: Solve for the Radius \( r \)

To solve for \( r \), divide both sides of the equation by \( 4 \pi \): \[ r^2 = \frac{154}{4 \pi} = \frac{154}{12.5664} \approx 12.25 \] Taking the square root of both sides: \[ r = \sqrt{12.25} \approx 3.5 \, \text{cm} \]

Step 3: Volume of the Sphere

The formula for the volume \( V \) of a sphere is: \[ V = \frac{4}{3} \pi r^3 \] Substituting \( r = 3.5 \, \text{cm} \) into this equation: \[ V = \frac{4}{3} \pi (3.5)^3 \] First, calculate \( (3.5)^3 \): \[ (3.5)^3 = 42.875 \] Now calculate the volume: \[ V = \frac{4}{3} \pi \times 42.875 \approx \frac{4}{3} \times 3.1416 \times 42.875 \approx 179.594 \, \text{cm}^3 \]

Conclusion:

The volume of the sphere is approximately \( 179.59 \, \text{cm}^3 \).

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