Question

when henry surveyed 45 seventh - grade students at random in the school cafeteria, he found that 3 out of 15 liked reggae music. using proportional reasoning, about how many of the 180 seventh - grade students in his school like reggae?
about 12 seventh - grade students like reggae music.
about 36 seventh - grade students like reggae music.
about 60 seventh - grade students like reggae music.
about 108 seventh - grade students like reggae music.

Explanation:

Step1: Set up the proportion

Let $x$ be the number of seventh - grade students who like reggae out of 180. The proportion is $\frac{3}{15}=\frac{x}{180}$.

Step2: Cross - multiply

$15x = 3\times180$.

Step3: Solve for $x$

First, calculate $3\times180 = 540$. Then $x=\frac{540}{15}=36$.

Answer:

B. About 36 seventh - grade students like reggae music.