In a sample of 50 bulbs, 2 were broken. About how many of 1,000 are…

Step by step

The question

Question: In a sample of 50 bulbs, 2 were broken.

About how many of 1,000 are broken?

1 The fraction in the sample

2 out of 50: that is 2/50.

The 50 bulbs are a sample: a small group that stands for everyone.

2 and 50 can both be divided by 2.

So it is 1/25.

2 Use it for everyone

We expect the same fraction of all 1,000: 1/25 of 1,000.

Of means times.

1,000 divided by 25 is 40.

That is about 40.

Careful!

A sample only shows about how many.

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

So about 40 bulbs are broken.

3 Check

Let's check: 40 out of 1,000.

Divide the top and the bottom by 40: 1/25, 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.