The radius of a hemispherical bowls is $6\text{cm}$. The capacity of the bowl is $\left(\text{Take } \pi=\frac{22}{7}\right)$
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
-
A$495.51\text{cm}^3$
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B$452.57\text{cm}^3$
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C$345.53\text{cm}^3$
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D$422\text{cm}^3$
Answer
Correct Answer: $452.57\text{cm}^3$
Explanation
### Concept & Formula
The capacity of a bowl is synonymous with its internal volume. For a hemisphere, the volume is exactly half of a full sphere.
$$ \text{Volume of Hemisphere} = \frac{2}{3}\pi r^3 $$
### Step-by-Step Solution
1. **Given:**
- Radius $r = 6\text{cm}$
- $\pi = \frac{22}{7}$
2. **Apply the Formula:**
- $\text{Volume} = \frac{2}{3} \times \frac{22}{7} \times (6)^3$
- $\text{Volume} = \frac{2}{3} \times \frac{22}{7} \times 216$
3. **Simplify and Calculate:**
- Divide $216$ by $3$ to get $72$.
- $\text{Volume} = 2 \times \frac{22}{7} \times 72$
- $\text{Volume} = \frac{44 \times 72}{7} = \frac{3168}{7}$
4. **Convert to Decimal:**
- $3168 \div 7 = 452.5714...$
- Rounding to two decimal places, we get $452.57\text{ cm}^3$.
### Exam Strategy & Shortcut
When multiplying $44 \times 72$, you can split it as $44 \times (70 + 2) = 3080 + 88 = 3168$. When dividing by $7$, notice that $7 \times 400 = 2800$ and $7 \times 50 = 350$, so the result must be slightly above $450$. Option (b) is the only reasonable match without fully completing the long division.
### Common Pitfall
Using the formula for the volume of a full sphere ($\frac{4}{3}\pi r^3$) instead of a hemisphere, which would yield exactly double the correct answer.
### Final Answer
Therefore, the correct answer is **$452.57\text{cm}^3$**.