Step by step
The question
Question: A die is rolled 30 times and 4 comes up 6 times.
Find the experimental probability of rolling a 4.
1 Times it happened over times tried
It happened 6 times out of 30 rolls.
So the experimental probability is 6/30.
Experimental probability comes from what really happened in the experiment.
6 and 30 can both be divided by 6.
So it is 1/5.
As a percent: 5 times 20 is 100.
1 times 20 is 20.
So it is 20%.
2 Compare with the theory
In theory, a die has 6 sides, so each number is 1 out of 6: about 16.7%.
Careful!
That is the theory.
The question asks what really happened: 20%.
20% is close to 16.7%.
With more rolls, it usually gets even closer.
3 Check
Let's check: 20% of 30 rolls should be the 6 times.
20% of 30 is 6.
So the answer is right!
Let's look back.
First: times it happened over times tried.
Then: compare with the theory.
Last: check.