Question

If 20% of a number is 35, what is 50% of that number?A. 55B. 70C. 87.5D. 175

Answer 1

Step 1

Find 100 percent of the number

and

Let x represent 100 percent of the number

$\begin{gathered} 20\text{\%}=\frac{20}{100}=0.2 \\ 100\text{\%}=\frac{100}{100}=1 \\ \frac{0.2}{1}=\frac{35}{x} \\ 0.2x=35 \\ \frac{0.2x}{0.2}=\frac{35}{0.2} \\ x=175 \end{gathered}$

Step 2

Find 50% of the number

and

Let y represent 50% of the number

$\begin{gathered} 50\text{\%=}\frac{50}{100}=0.5 \\ \frac{0.5}{1}=\frac{y}{175} \\ \end{gathered}$$\begin{gathered} 0.5\times175=y \\ y=87.5 \end{gathered}$

Hence, 50% of the number = 87.5