Step by step
The question
Question: Is it a good sample?
To find how long students sleep, ask 50 students picked at random from the school list.
1 Look at who was asked
They ask 50 students picked at random from the school list.
50 students picked at random from the school list
A good sample is like the whole group.
Everyone has the same chance to be picked.
good sample = like the whole group
2 See if they are all alike
They are picked at random.
So everyone in the group has the same chance.
The sample is like the whole group.
= picked at random → everyone has the same chance
So yes: it is a good sample.
= yes: a good sample
3 Check
Let's check: could every person in the group be picked?
Yes.
So the answer is right!
every person could be picked ✓
Let's look back.
First: look at who was asked.
Then: see if they are all alike.
Last: check.
Answer
= yes: a good sample