CBSE
2026
Class Class 10 · Mathematics
1 Marks · Mcq
✅ Verified
A hemispherical bowl is made of steel of thickness 1 cm. The outer radius of the bowl is 6 cm. The volume of steel used (in cm$^3$) is :
A. $182\pi$
B. $\dfrac{182}{3}\pi$
C. $\dfrac{682}{3}\pi$
D. $\dfrac{364}{3}\pi$
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✅ Answer & Solution
✅ Correct Answer: B
**Step 1 — Find both radii.**
$$R = \text{outer radius} = 6 \text{ cm}, \qquad r = \text{inner radius} = 6 - 1 = 5 \text{ cm}$$
**Step 2 — Write the formula for the volume of the steel (hollow hemisphere).**
$$V = \frac{2}{3}\pi R^3 - \frac{2}{3}\pi r^3 = \frac{2}{3}\pi\left(R^3 - r^3\right)$$
**Step 3 — Substitute the values.**
$$V = \frac{2}{3}\pi\left(6^3 - 5^3\right) = \frac{2}{3}\pi(216 - 125) = \frac{2}{3}\pi(91)$$
**Step 4 — Simplify.**
$$V = \frac{182}{3}\pi \text{ cm}^3$$
**Answer : (B) $\dfrac{182}{3}\pi$**
✅ Verified by Super Admin