Page 434 - Math Smart - 7

Estimating probabilities

Freya wants to find the probability that it will rain on any one day in September.
So, she records the weather over 15 days in September in the bar chart below.

Weather over 15 days In September

Number of
days 4_

3-
2-
I
1 -

Sunny Cloudy Rainy
Weather

Using the information Freya recorded, we can find the experimental probability
hink and Share that it will rain on any one day in September.

Number of favourable outcomes = 5 days
Can Freya calculate the
theoretical probability that Total number of days = 15 days
it will rain on any one day Experimental probability that it will rain on any one day in September = ^
in September? Why or why
1
not? - 3
The experimental probability that it will rain on any one day in September is 3.

Sometimes, it is not possible for us to know the theoretical probabilities of the
outcomes. We can use the experimental probabilities to estimate the probability
of an outcome.

When your favourite sports team plays a match, there are three possible
outcomes.

The team loses Your team draws The team wins

You would not know what the outcome will be. You check the previous scores of
30 matches played by each team.

Experimental
Team Matches won in the past year Frequency
probability

Your team 22 30 =0.73
Opposing
i - 0-27
team
^30 UNITir^l Probability