Calculating Probabilities
If a set of events have an equal chance of
occurring, it is possible to calculate probabilities.
For example, you can calculate the probability of
rolling a 4 on a die because the 4 has the same
chance of occurring as the other numbers.
Calculating Probabilities
If you can calculate probabilities, you can use this
simple method:
The probability of
an event happening
=
The number of
results you want
The number of
possible results
Calculating Probabilities
If you can calculate probabilities, you can use this
simple method:
The probability of
rolling a 4 on a
normal die
=
1 side with the number 4
6 possible sides
Calculating Probabilities
If you can calculate probabilities, you can use this
simple method:
The probability of
rolling a 4 on a
normal die
=
1
6
Calculating Probabilities
Which of these statements are true about the
word MATHEMATICAL?
•The probability of picking a vowel is 50 %
because a letter picked is either a vowel or it
isn’t.
False, there are less vowels than consonants.
•The probability of picking a vowel is 5
because there are 5 vowels out of
12 letters.
True
12
Calculating Probabilities
This spinner represents all of class
6B
other
walk
bike
car
bus
How class 6b get to school
Decide which of these
statements are true.
Calculating Probabilities
The chance of landing on a
person who said bike or car is
the same as landing on a
person who walks. True
other
walk
bike
car
bus
The chance of getting
“bike” is the same as
getting “car”
False
Calculating Probabilities
The chance of getting “car” is
1
2
other
walk
bike
car
bus
False
The chance of getting car
is 25 %
True