Question

from the given figure, find the volume of the paper towel (use π = 3.142)

Explanation:

Step1: Recall volume formula for cylinder

The volume of a cylinder is $V=\pi r^{2}h$. We will find the volume of the outer - cylinder and the inner - cylinder and then subtract.

Step2: Calculate volume of outer - cylinder

For the outer - cylinder, $r = 8$ cm and $h = 20$ cm. Using the formula $V_1=\pi r_1^{2}h$, we have $V_1 = 3.142\times8^{2}\times20=3.142\times64\times20 = 4021.76$ $cm^{3}$.

Step3: Calculate volume of inner - cylinder

For the inner - cylinder, $r = 5$ cm and $h = 20$ cm. Using the formula $V_2=\pi r_2^{2}h$, we have $V_2=3.142\times5^{2}\times20=3.142\times25\times20 = 1571$ $cm^{3}$.

Step4: Calculate volume of paper - towel

The volume of the paper - towel $V = V_1 - V_2$. So $V=4021.76 - 1571=2450.76$ $cm^{3}$.

Answer:

$2450.76$ $cm^{3}$