Grade 9 | Unit 9.3 | Page 11
WHAT ARE MY CHANCES?
Calculate the probabilities of the following. Circle the correct answer.
Probability = number of favourable outcomes
total number of possible outcomes
Activity 1 - dice throwing
1. You bet that the die will land on a number higher than 4. What is the probability of getting a number higher
than 4 when you roll a die?
b. 2/6 (or 1/3)
c. 4/6 (or 2/3)
(Hint: how many numbers are there on a die that are higher than 4? Divide this number by the total number
of [equally likely] possible numbers one can throw with a die.)
Activity 2: - simple slot machine
2. Sipho is going to spin the arrow on a four coloured wheel that has four equal area segments: blue, green,
yellow and red. Sipho bets on the colour blue. What is the probability that Sipho will win and that the arrow
will stop on blue?
b. 2/4 (or 1/2)
(Hint: How many blue coloured segments are there on the wheel? Divide this number by the total number of
colours on the wheel.)
Activity 3 - roulette wheel
3. A roulette wheel has 37 numbers: 18 black, 18 red and a green “0”. Of the 37 numbers, 18 are even and
18 are uneven (or odd), and then there's “0”.When the wheel is spun, all numbers are equally likely to appear.
On a single spin of the wheel, what is the probability that the ball will land on your bet of a black number?
(Hint: divide the number of black numbers by the total number of numbers on the wheel)
4. On a single spin of the wheel, what is the probability that the ball will land on “0”?
(Hint: how many “0” numbers are there? Divide this by the total number of numbers on the roulette wheel.)
5. And here is a tricky one: On a single spin of the wheel, what is the probability that the ball will land on an
even number less than 9?
(Hint: first of all determine how many even numbers there are less than 9. Then divide this number by the total
number of numbers on the roulette wheel.)
Learning Activity - page i