Question

Solve each proportion. If necessary, round to nearest hundredth.

$\frac{3}{8}=\frac{15}{a}$

Short answer

The value of $a=40$.

Step-by-step solution

Step-1. Define equivalent ratios.

Equivalent ratios are two ratios which have same relationship between the numbers.

Step-2. Find the cross products.

The given ratios can be simplified by doing cross product:

$\begin{array}{c}\frac{3}{8}=\frac{15}{a}\\ a\left(3\right)=\left(15\right)8\end{array}$

Step-3. Simplify for a.

To further simplify, divide each side by 3.

$\begin{array}{c}a\left(3\right)=\left(15\right)8\\ 3a=\text{120}\\ \frac{3a}{3}=\frac{120}{3}\\ a=40\end{array}$

Therefore, the value of $a=40$.