Marion Middle School has 600 students. Mike surveys a random sample of 30 students and finds that 7

Marion Middle School has 600 students. Mike surveys a random sample of 30 students and finds that 7 of them play a musical instrument. How many students at the school are likely to play a musical instrument?

Set up a proportion of those that play musical instruments to total students where m is the amount of students in the 600 who play a musical instrument:
7/30 = m/600

Typing this proportion into our search engine, we get:
m = 140