Probability

Assign Probabilities

1

Match Probability Words to Numbers

Draw a line to match each probability word to its number.

Impossible
Unlikely
Even chance
Certain
1 or 100%
0 or 0%
1/2 or 50%
1/4 or 25%
2

Write the Probability (Fractions)

Write the probability as a fraction.

Rolling a 3 on a standard die: ___

Flipping heads on a coin: ___

Drawing a red card from a deck (26/52): ___

Rolling an even number on a die: ___

3

More Probability Fractions

Write the probability as a fraction.

Rolling a number > 4 on a die: ___

Drawing a heart from a deck (13/52): ___

Rolling a 7 on a standard die: ___

Landing on any number on a die: ___

4

Probability Quick Check

Circle the correct probability.

P(heads on a coin) = ?

0
1/2
1

P(rolling a 5 on a die) = ?

1/5
1/6
5/6

P(rain on a sunny day) is closest to:

0
1/2
1

P(sun rises tomorrow) is closest to:

0
1/2
1
5

Sort: Impossible to Certain

Sort each event by likelihood.

Rolling a 7 on a die
Flipping heads
Rain sometime this year
Rolling a 1 on a die
Sun sets tonight
Impossible
Unlikely
Even chance
Likely
Certain
6

Probability Number Line

Explain what each probability means.

P = 0 means: ___

P = 1/2 means: ___

P = 1 means: ___

Where would P = 1/4 go? ___

7

Match Fractions, Decimals & Percentages

Match each probability in its three forms.

1/4
1/2
3/4
1/5
0.5 = 50%
0.75 = 75%
0.2 = 20%
0.25 = 25%
8

Convert Probabilities

Write each probability as fraction, decimal AND percentage.

5 red out of 20. P(red) = ___ = ___ = ___%

3 blue out of 8. P(blue) = ___ = ___ = ___%

2 green out of 10. P(green) = ___ = ___ = ___%

9

More Conversions

Convert each probability to all three forms.

P = 1/8. Decimal: ___. Percentage: ___%

P = 0.6. Fraction: ___. Percentage: ___%

P = 40%. Fraction: ___. Decimal: ___

P = 3/10. Decimal: ___. Percentage: ___%

10

Spinner Probabilities

Spinner has 8 sections: 3 red, 2 blue, 2 green, 1 yellow.

P(red) = ___ = ___ = ___%

P(blue) = ___ = ___ = ___%

P(yellow) = ___ = ___ = ___%

P(not red) = ___ = ___ = ___%

11

Complementary Events

P(not happening) = 1 − P(happening).

P(rain) = 0.3. P(no rain) = ?

0.3
0.7
1.3

P(win) = 1/4. P(not win) = ?

1/4
3/4
4/4

P(heads) = 50%. P(tails) = ?

25%
50%
75%
12

Compare Probabilities

Circle the more likely event.

More likely?

P = 1/3
P = 0.4

More likely?

P = 25%
P = 1/3

More likely?

P = 0.6
P = 55%

More likely?

P = 3/8
P = 0.35
13

Probability Problems

Solve each problem.

Bag: 3 red, 5 blue, 2 green. P(blue) = ___ (all 3 forms)

Spinner 1–8. P(number > 5) = ___

Bag: 4 red, 6 blue. Add 2 red. P(red) now = ___

14

Probability Reasoning

Explain your thinking.

If P(event) = 0, what does that tell you? ___

If P(event) = 1, what does that tell you? ___

Can a probability be greater than 1? ___

15

Home Activity: Probability Games

Explore probability at home!

  • 1Flip a coin 20 times. What fraction were heads?
  • 2Put coloured counters in a bag. Predict then test.
  • 3Roll a die 30 times. Compare fraction of 6s to 1/6.
  • 4Design a spinner: blue 50%, red 25%, green 25%.
  • 5Play a card game and calculate probabilities.
16

Expressing Probability Three Ways

Express each probability as a fraction, decimal and percentage.

Rolling a 5 on a fair die: ___ / ___ / ___

Drawing a red card from a standard deck: ___ / ___ / ___

Landing on blue (3 of 8 sections): ___ / ___ / ___

Drawing a vowel from A, E, I, O, U, B, C: ___ / ___ / ___

17

Match Probability to Event

Match each event to its most likely probability.

Sun rises tomorrow
Rolling a 7 on a standard die
Flipping tails on a fair coin
Drawing an ace from a full deck
1/2
4/52
0
1
18

Probability Experiment Results

A spinner has red, blue, green, yellow (equal sections). Spun 80 times. Each circle = 5 spins. Answer the questions.

Red
Blue
Green
Yellow
1

How many times was blue spun?

2

Expected per colour (80 spins, 4 equal sections)?

3

Which colour matched expected exactly?

19

Colour Counter Experiment

Record probability experiment results — 20 draws with replacement.

ItemTallyTotal
Red
Blue
Green
Yellow
20

Complementary Probability

Calculate the probability of the complement.

P(rain tomorrow) = 0.3. P(no rain) = ___

P(rolling a 6) = 1/6. P(not rolling a 6) = ___

P(drawing a heart) = 1/4. P(not a heart) = ___

Explain the complementary rule in your own words: ___

21

Probability on the Scale

Circle where each event sits on the probability scale 0–1.

Drawing a prime from 1–10:

0.4
0.5
0.6

Rolling less than 4 on a die:

0.5
1/2
3/6

Getting a tail on a fair coin:

0
0.5
1

Choosing a consonant from B,C,D,E,F:

3/5
0.4
0.6
22

Sample Space

List the sample space and calculate probability.

Fair coin flipped twice. All outcomes: ___

P(2 heads) = ___

P(at least 1 tail) = ___

A die rolled. P(even) = ___, P(prime) = ___

23

Sort Probabilities Lowest to Highest

Write these in order from least likely to most likely.

P = 0.75
P = 1/5
P = 60%
P = 3/8
P = 0.1
P = 90%
Least likely
Most likely
24

Probability from a Table

A bag has: 5 red, 3 blue, 2 green, 10 total. Answer the questions.

P(red) = ___

P(blue) = ___

P(not green) = ___

P(red or blue) = ___

How many red balls to make P(red) = 1/2? ___

25

Probability Pairs Sum to 1

Complete each pair. Probabilities of all outcomes must sum to 1.

1
?
?
1
?
?
1
?
?
1
?
?
26

Design a Probability Game

Design a spinner game for two players.

Sections on your spinner (colours and sizes): ___

P(Player 1 wins per spin) = ___

P(Player 2 wins per spin) = ___

Is your game fair? How do you know? ___

27

Probability Calculation Steps

Put these steps in order for calculating probability.

?
Write P(event) as a fraction
?
Count the total possible outcomes
?
Identify the event
?
Simplify the fraction
?
Count favourable outcomes
28

Theoretical vs Experimental

You roll a die 60 times. You get six 1s.

Theoretical P(1) = ___

Experimental P(1) from your results = ___

Are they the same? Why or why not? ___

How could you get closer to theoretical? ___

29

Match Fraction, Decimal, Percentage

Match equivalent probabilities.

1/4
3/5
7/10
1/8
0.125
0.25
60%
70%
30

Real-World Probability

Answer each real-world probability question.

Weather forecast: 70% chance of rain. P(no rain) = ___

1 in 6 chance of winning a prize. P(winning) as decimal = ___

10% chance of server error. In 200 requests, expected errors = ___

31

Identify the Correct Probability

Circle the correct answer.

P(rolling > 4) on die:

1/3
2/3
1/2

P(ace) from deck of 52:

4/52
1/4
4/13

P(sum = 7) rolling 2 dice:

6/36
7/36
1/6

P(drawing even from 1–10):

1/2
4/10
6/10
32

Probability and Fairness

Evaluate whether each game is fair.

Game: roll a die, win if prime, lose if composite. Fair? ___

Spinner: 3 equal sections but 2 say 'Player A wins'. Fair? ___

Design a fair two-player coin game: ___

33

Probability Summary

Write what you know about probability.

Probability is always between ___ and ___.

Formula: P(event) = ___

Three events with probabilities 0, 0.5 and 1: ___

One real-life use of probability: ___