3 of 10 students bike to school. About how many of 500 bike?

Step by step

The question

Question: 3 of 10 students bike to school.

About how many of 500 bike?

1 The fraction in the sample

3 out of 10: that is 3/10.

The 10 students are a sample: a small group that stands for everyone.

2 Use it for everyone

We expect the same fraction of all 500: 3/10 of 500.

Of means times.

500 divided by 10 is 50.

Then times 3.

That is about 150.

Careful!

A sample only shows about how many.

So the answer is a good guess, not an exact count.

So about 150 students bike.

3 Check

Let's check: 150 out of 500.

Divide the top and the bottom by 50: 3/10, the same fraction as the sample.

So the answer is right!

Let's look back.

First: the fraction in the sample.

Then: use it for everyone.

Last: check.