The curved surface area of a cylindrical pillar is 264 m 2and its volume is 924 m 3. Find the ratio of its diameter and its height:
7 ∶ 3
To determine the ratio of the diameter and height of a cylindrical pillar, we need to use the given curved surface area and volume. Let's denote the radius of the cylindrical pillar as $\text{r}$ and its height as $\text{h}$.
First, recall the standard formulas for a cylinder:
From the question, we are provided with the following information:
Using the given data and the formulas, we can set up two equations:
To find the radius $\text{r}$, we can divide Equation 2 by Equation 1. This step helps eliminate the height $\text{h}$ and $\pi$ from the equations, allowing us to solve directly for $\text{r}$.
$\frac{\text{Volume}}{\text{Curved Surface Area}} = \frac{\pi\text{r}^2\text{h}}{2\pi\text{rh}}$
Substitute the given values:
$\frac{924}{264} = \frac{\pi\text{r}^2\text{h}}{2\pi\text{rh}}$
Simplify the right side of the equation:
$\frac{924}{264} = \frac{\text{r}}{2}$
Now, solve for $\text{r}$:
$\text{r} = 2 \times \frac{924}{264}$
To simplify the fraction $\frac{924}{264}$, we can divide both the numerator and the denominator by common factors. Both are divisible by 12:
$924 \div 12 = 77$
$264 \div 12 = 22$
So, the fraction becomes $\frac{77}{22}$. This can be further simplified by dividing both by 11:
$\frac{77}{22} = \frac{7}{2}$
Now, substitute this simplified fraction back into the equation for $\text{r}$:
$\text{r} = 2 \times \frac{7}{2}$
$\text{r} = 7 \, \text{m}$
So, the radius of the cylindrical pillar is $7 \, \text{m}$.
Next, we use Equation 1 (the curved surface area formula) and the value of $\text{r}$ we just found to calculate the height $\text{h}$.
$2\pi\text{rh} = 264$
Substitute $\text{r} = 7 \, \text{m}$ and use $\pi = \frac{22}{7}$:
$2 \times \frac{22}{7} \times 7 \times \text{h} = 264$
$2 \times 22 \times \text{h} = 264$
$44\text{h} = 264$
Now, solve for $\text{h}$:
$\text{h} = \frac{264}{44}$
$\text{h} = 6 \, \text{m}$
So, the height of the cylindrical pillar is $6 \, \text{m}$.
The diameter $\text{d}$ is twice the radius $\text{r}$:
$\text{d} = 2\text{r}$
Substitute $\text{r} = 7 \, \text{m}$:
$\text{d} = 2 \times 7$
$\text{d} = 14 \, \text{m}$
So, the diameter of the cylindrical pillar is $14 \, \text{m}$.
Finally, we need to find the ratio of the diameter to the height ($\text{d} : \text{h}$).
$\text{d} : \text{h} = 14 : 6$
To simplify the ratio, divide both numbers by their greatest common divisor, which is 2:
$\frac{14}{2} : \frac{6}{2} = 7 : 3$
Thus, the ratio of the diameter and its height is $7 : 3$.
| Quantity | Value |
|---|---|
| Radius (r) | $7 \, \text{m}$ |
| Height (h) | $6 \, \text{m}$ |
| Diameter (d) | $14 \, \text{m}$ |
| Ratio of Diameter to Height (d : h) | $7 : 3$ |
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