Question

when andrei surveyed 36 random seventh - grade students in the lunchroom, he found that 7 out of 9 would like to try or have already tried snorkeling. using proportional reasoning, about how many of the 810 seventh - grade students in his school would like to snorkel?
about 157 seventh - grade students would like to snorkel.
about 202 seventh - grade students would like to snorkel.
about 630 seventh - grade students would like to snorkel.
about 720 seventh - grade students would like to snorkel.

Explanation:

Step1: Set up the proportion

Let $x$ be the number of students who would like to snorkel out of 810 students. The proportion is $\frac{7}{9}=\frac{x}{810}$.

Step2: Cross - multiply

$9x = 7\times810$.

Step3: Solve for $x$

$x=\frac{7\times810}{9}$. First, calculate $7\times810 = 5670$. Then, $\frac{5670}{9}=630$.

Answer:

C. About 630 seventh - grade students would like to snorkel.