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# Find the radius of a sphere whose surface area is 154 cm^{2}.

**Solution:**

Given: The surface area of a sphere is 154 cm^{2}.

The surface area of the sphere of radius r, SA = 4πr^{2}.

The surface area of the sphere = 154 cm^{2}

4πr^{2} = 154 cm^{2}

r^{2} = 154/4π

r^{2} = (154/4) (7/22)

r^{2} = (154 × 7) / (4 × 22)

r^{2} = (49/4)

r = (7/2) = 3.5 cm

Thus, the radius of the sphere whose surface area is 154 cm^{2} is 3.5 cm.

**☛ Check: **Class 9 Maths NCERT Solutions Chapter 13

**Video Solution:**

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

Class 9 Maths NCERT Solutions Chapter 13 Exercise 13.4 Question 6

**Summary:**

The radius of a sphere whose surface area is 154 cm^{2 }is equal to 3.5 cm.

**☛ Related Questions:**

- Find the surface area of a sphere of radius: i) 10.5 cm ii) 5.6 cm iii) 14 cm
- Find the surface area of a sphere of diameter: i) 14 cm ii) 21 cm iii) 3.5 m
- Find the total surface area of a hemisphere of radius 10 cm. (Use π = 3.14)
- The radius of a spherical balloon increases from 7 cm to 14 cm as air is being pumped into it. Find the ratio of surface areas of the balloon in the two cases.

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