5 minutes to get your things
together and try this exercise
Starter
Place the following events on the probability scale
7A will win sports day
7A will win sports day
0
½
1
I am
looking for
students
who can
use the
correct
notation for
probability
Chapter 28: Chance
(2) Calculating Probability
Cannot occur at
the same time
Today we will learn how
to
calculate the probability
of an exclusive event
How do we calculate probabilities?
What is the probability of
choosing the following
colors?
0.3
Red 3/10
Blue 5/10
0.5
1/2
Green 2/10
0.2
1/5
How do we calculate probabilities?
Probability of an event = number of successful outcomes
total number of outcomes
So from my packet of
the next one is
white and yellow?
We need some information:
3/16
3 oranges
3 green
3/16
4 whites
1 yellow
1/16
5 purple
1/4
5/16
what is the probability
orange, green, purple,
In my ‘bag of sweets for good children’ I have 20
sweets; 3 of them are my favorite éclairs.
• what is the probability that the first good child
picks an éclair? 3/20
• what is the probability that the first good child
does not pick an éclair?
17/20
• The probability of choosing a diamond card
from a standard pack of cards is 0.25 what is
the probability of choosing any other suit?
0.75
• The probability I loose a thumb wrestling match
is 0.85, what is the probability I win?
0.15
Bonus Question - Easy
• The letters of the word HIPPOPOTAMUS
are placed in a tub and a letter is taken at
random. What is the probability of taking
out:
• H 1/12
• M 1/12
• O 1/6
• P 1/4
Bonus Question - Hard
A bag contains 6 red balls and some white
balls.
When a white ball is taken from the bag at
random, the probability that it is red is 3/5,
how many white balls are in the bag?
6
4
X
10
3/5
2/5
5/5
1
Now its Your Turn:
Page 352 from the E1 books
Exercise E, F and G