MCQ
If the surface area of a sphere is $616\ cm \ 2$ its diameter $($in $\ cm)$ is :
- A$7$
- ✓$14$
- C$28$
- D$56$
✓
Answer
Correct option: B.
$14$
Surface area of a sphere $= 616 \mathrm{~cm}^2$
$\Rightarrow4\pi\text{r}^2=616$
$\Rightarrow4\times22\times\text{r}^2=616$
$\Rightarrow\text{r}^2\frac{616\times7}{22\times4}$
$\Rightarrow\text{r}=7\text{ cm}$
So, the diameter $=2\text{r}=2\times7=14\text{ cm}.$
$\Rightarrow4\pi\text{r}^2=616$
$\Rightarrow4\times22\times\text{r}^2=616$
$\Rightarrow\text{r}^2\frac{616\times7}{22\times4}$
$\Rightarrow\text{r}=7\text{ cm}$
So, the diameter $=2\text{r}=2\times7=14\text{ cm}.$
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