how to solve for ratio? help needed

Question

In the school cafeteria, 3 out of every 5 students buy a sandwhich for lunch. Which represents the ratio of students that buy a sandwhich to students who do not buy a sandwhich.

2/5 right ?

Answer 1

Given this ratio x:y

In English, this would mean for every "x" amount of something there are "y" amount of something else.

In our example...

For every 5 students...

3 student buy a sandwich

2 student do not buy a sandwich

2:5 would mean for every 2 student who buy a sandwich 5 do not. (which is incorrect)

We need 3:2 which means for every 3 student who buy a sandwich 2 do not. This is correct.

Hope this helps!

Answer 2

2/5 is the ratio of students who do not buy a sandwich. What the question is asking is not what the ratio is of students who do not buy a sandwich, but what is the ratio between students who buy sandwiches and students who don't buy sandwiches.

For every 3 students who do buy a sandwich for lunch, we have 2 students who do not buy a sandwich for lunch. Therefore, our ratio of students who buy sandwiches to students who do not buy a lunch is 3/2, or 3:2.