Question

2. The ratio of radii of two cylinders is 1:2 and heights are in the ratio 2:3. Find the ratio of their volumes.

Answer 1

Answer: $\frac{1}{6}$ or $1:6$

Step-by-step explanation:

The volume of a cylinder can be found with the following formula:

$V=\pi r^2h$

Where "r" is the radius and "h" is the height of the cylinder.

In this case, let be:

- $V_1$ the volume of one of this cylinders and $V_2$ the volume of the other one.

- $r_1$ the radius of the first one and $r_2$ the radius of the other cylinder.

- $h_1$ the height of one of them and $h_2$ the height of the other cylinder.

Then:

$V_1=\pi r_1^2h_1\\\\V_2=\pi r_2^2h_2$

Therefore, you know this:

$\frac{V_1}{V_2} =\frac{\pi r_1^2h_1}{\pi r_2^2h_2}$

Simplifying, you get:

$\frac{V_1}{V_2} =\frac{ r_1^2h_1}{ r_2^2h_2}$

Now, knowing the ratios given in the exercise, you can substitute them into the equation:

$\frac{V_1}{V_2} =\frac{1^2*2}{ 2^2*3}$

Evaluating, you get:

$\frac{V_1}{V_2} =\frac{2}{ 4*3}\\\\\frac{V_1}{V_2} =\frac{2}{12}\\\\\frac{V_1}{V_2} =\frac{1}{6}$