Question

Helena is watching a movie ontelevision. She notices that there are9. min of commercials for every hof the movie.What is the unit rate of minutes of commercials per hour of the movie?

Answer 1

$unit\text{ rate = = 18 }\frac{1}{2}\frac{\min s}{hr}\text{ (option D)}$

Explanation:

$9\frac{1}{4}\text{minutes of commercial = }\frac{1}{2}\text{hour of Television}$

A unit rate of minutes of commercials per hour of the movie means to find minute of commercial in 1 hour:

$\begin{gathered} \frac{1}{2}\text{hour = 9}\frac{1}{4}\min \\ 1\text{ hour = x} \\ \text{cross multiply: } \\ x(\frac{1}{2})\text{ = 1(9}\frac{1}{4}) \\ \frac{x}{2\text{ }}=\text{ }\frac{37}{4}\text{ cross multiply} \\ 4x\text{ = 2}\times37 \\ x\text{ = }\frac{74}{4}\text{ = }\frac{37}{2} \\ x\text{ = 18 }\frac{1}{2} \end{gathered}$

The unit rate of minutes of commercials per hour of the movie = 18 1/2 (option D)