Question

All students in Ridgewood Junior High School either got their lunch in the school cafeteria or brought it from home on Tuesday. 5% of students brought their lunch. 49 students brought their lunch. How many students in total are in Ridgewood Junior High School?

Answer 1

980

Explanation:

A simple way to do this is to do a quick estimate, which I truthfully did.

Since 5% of 1000 is 50, I simply counted back.

5% of 990 is 49.5. Notice the slight change? Use this to your advantage. What would happen if we subtracted 10 from 990, just like we did with 1000? This would be equivalent to removing 0.5 from 49.5.

5% of 980 is 49.