Theoretical Probability
What is the probability of rolling a 6 on a standard die?
1/6
Define experimental probability in one sentence.
The probability based on actual results from an experiment.
What does “outcome” mean in probability?
A possible result of a chance experiment.
Convert 1/2 to a decimal.
0.5
You flip a coin. What is the probability of heads OR tails?
1 (certain outcome; these are the only two options)
A bag has 3 red, 2 blue, and 1 green marble. What is P(blue)?
2/6 or 1/3
You roll a die 10 times. It lands on 2 five times. What is the experimental probability of getting a 2?
5/10 or 1/2
What is a “sample space”? Give an example.
The set of all possible outcomes (e.g., {Heads, Tails}).
Convert 3/4 to a percentage.
75%
A spinner has 4 equal colours. What’s the probability of getting red twice in a row?
1/4 × 1/4 = 1/16
What is the probability of getting an even number when rolling a die?
3/6 or 1/2
If you flip a coin 20 times and get 12 heads, what’s the experimental probability of heads?
12/20 or 3/5
Define “equally likely”.
Outcomes that have the same probability of occurring.
Write 0.25 as a fraction and a percentage.
1/4 and 25%
You roll two dice. What is the probability of getting a sum of 7?
6/36 or 1/6
What is the probability of drawing a king from a 52-card deck?
4/52 or 1/13
How can experimental probability be different from theoretical probability?
Because of variability in outcomes during trials; real results may not match expected.
What does “complementary event” mean?
Events that together include all possible outcomes (e.g., heads or not heads).
Convert 0.6 to a fraction and percentage.
3/5 and 60%
A bag has 5 yellow, 3 green, and 2 red balls. What’s the probability of NOT getting red?
8/10 or 4/5
What is the probability of drawing two red cards in a row without replacement from a 52-card deck?
(26/52) × (25/51) = 650/2652 ≈ 0.245
Describe an experiment you could conduct to explore probability in your own life.
Open-ended; e.g., tracking colours of cars passing by, outcomes of spinner games, etc.
What’s the difference between a trial and an experiment?
A trial is one repetition; an experiment is a series of trials.
A class survey shows 18/24 students like pizza. Express this as a decimal and percentage.
0.75 and 75%
A teacher pulls names randomly from a hat. There are 6 girls and 4 boys. What is the probability of pulling a boy, replacing, and then pulling a girl?
(4/10) × (6/10) = 24/100 or 6/25