Step by step
The question
Question: A spinner landed on red 9 times in 15 spins.
Predict the reds in 250 spins.
1 Times it happened over times tried
It happened 9 times out of 15 spins.
So the experimental probability is 9/15.
P(red) = 915
Experimental probability comes from what really happened in the experiment.
experimental = what really happened
9 and 15 can both be divided by 3.
So it is 3/5.
= 9 ÷ 315 ÷ 3 = 35
2 Predict
We expect the same fraction in 250 spins: 3/5 of 250.
Of means times.
= 35 × 250
250 divided by 5 is 50.
250 ÷ 5 = 50
Then times 3.
= 3 × 50
So about 150.
= ≈ 150
Careful!
A prediction is only about how many.
The next spins can come out a bit different.
Careful: about, not exactly: chance can change it
3 Check
Let's check: 150 out of 250 is 3/5, the same fraction as before.
So the answer is right!
150250 = 35
Let's look back.
First: times it happened over times tried.
Then: predict.
Last: check.
Answer
Careful: about, not exactly: chance can change it