When calculating an experimental probability, we are comparing the number of times the event occurs to the number of times the experiment is done.
P=Times the Event Occurs/Times the Experiment Is Done
This is very similar to the Probability Formula.
Below we can see the results of a survey of 100 randomly selected students at a 2000-student high school. Now we can find the experimental probability that a student selected at random does not plan to go to trade school.
Response
Number of Responses
Go to community college
24
Go to 4-year college
43
Take a year off before college
12
Go to trade school
15
Do not plan to go to college
6
In the table, there is a total of 24 students who plan to go to community college, 43 whose plan is going to a 4-year college, 12 who plan taking a year off before college, 15 who plan going to trade school, and 6 who do not plan to go to college. The sum of these values is the number of possible outcomes.
24+43+12+15+6= 100
We want to find the probability of randomly selecting a student who does not plan to go to trade school. Note that this is the complement of selecting a student who plans to go to trade school. The sum of the probability of an event and the probability of its complement is 1.
P(Event)+P(Not event)=1
Let's start by finding the probability of selecting a student who plans to go to trade school, which will be our event. The number of times the event occurs is 15, and the number of times the experiment is done is 100.
P(Trade school)= Number of Trade School Plans/Number of Plans
⇓
P(Trade school)= 15/100
The experimental probability of selecting a student who plans to go to trade school is 15100. Let's now find the probability of its complement, P(Not Trade School), which is the probability of selecting a student who does not plan to go to trade school.
