Basic College Mathematics (10th Edition)

$\frac{2}{5}$ responded 4 hours or more, 408 responded 4 hours or more,
To find the fraction of people and the number of people willing to wait four hours or more you must combine the group who responded 4 hours with the group who responded 8 hours or more. The graph indicates the $\frac{1}{4}$ responded 8 hours or more and $\frac{3}{20}$ responded 4 hours. To add these fractions together you must find the lowest common denominator and restate both fractions using the lowest common denominator. The lowest common denominator is 20, so only $\frac{1}{4}$ needs to be converted. $\frac{1}{4}$ = $\frac{1 \times 5}{4 \times 5}$ = $\frac{5}{20}$ Now you can add the two fractions to find the fraction of people who responded 4 hours or more. $\frac{5}{20}$ + $\frac{3}{20}$ = $\frac{8}{20}$ = $\frac{8 \div 4}{20 \div 4}$ = $\frac{2}{5}$ Multiply the total number people of surveyed by $\frac{2}{5}$ to find the number who responded 4 hours or more. $1020 \times \frac{2}{5}$ = $\frac{2040}{5}$ = $\frac{2040 \div 5}{5 \div 5}$ = $\frac{408}{1}$ = 408