Question

what percent of the lifeguards were working that day? 40%
a student answered 72 questions correctly and scored a 90%. how many questions were on the test?

Explanation:

Step1: Define the formula for percentage

The formula for percentage is $\text{Percentage} = \frac{\text{Part}}{\text{Whole}} \times 100\%$. Here, the part is the number of correct answers (72), and the percentage is 90%. We need to find the whole (total number of questions). Let the total number of questions be $x$. So, $90\%=\frac{72}{x}\times 100\%$.

Step2: Solve for x

First, rewrite the percentage as a decimal. $90\% = 0.9$ and $100\% = 1$. The equation becomes $0.9=\frac{72}{x}$. Cross - multiply to get $0.9x = 72$. Then, divide both sides by 0.9: $x=\frac{72}{0.9}=80$.

Answer:

80