Q14. - Algebra 1

Question

Use the percent proportion to find the following number.

What is 25% of 18?

Step-by-Step Solution

Answer

25% of 18 is 4.5.

Step 1. Definition of percent.

Percent of a number is defined as the ratio of number and 100.

Step 2. Formula Used.

The ratio of part x of some number y is equal to the percent is written as.

$\frac{x}{y}=\frac{p}{100}$

Step 3. Find the percent proportion.

Percent = 25, y = 18 and x = ?

$$\begin{gathered} \frac{x}{y} =\frac{p}{100} \\ \frac{x}{18}=\frac{25}{100} \left[\mathrm{crossmultiply}\right] \\ x\times 100=18\times 25 \\ 100x=450 \left[\mathrm{dividebothsideby}50\right] \\ \frac{100x}{50}=\frac{450}{50} \\ 2x=9 \\ x=\frac{9}{2} \\ x=4.5 \end{gathered}$$

Hence, 25% of 18 is 4.5.