14 of 35 students play an instrument. About how many of 700 play an…

Step by step

The question

Question: 14 of 35 students play an instrument.

About how many of 700 play an instrument?

1 The fraction in the sample

14 out of 35: that is 14/35.

The 35 students are a sample: a small group that stands for everyone.

14 and 35 can both be divided by 7.

So it is 2/5.

2 Use it for everyone

We expect the same fraction of all 700: 2/5 of 700.

Of means times.

700 divided by 5 is 140.

Then times 2.

That is about 280.

Careful!

A sample only shows about how many.

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

So about 280 students play an instrument.

3 Check

Let's check: 280 out of 700.

Divide the top and the bottom by 140: 2/5, 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.