Vocabulary
What do we call the chance that something will happen?
Probability
Rolling a 6-sided die: The chance of rolling a 3 is 1/6. Is this theoretical or experimental?
theoretical
If two events are mutually exclusive, what does that mean?
They cannot happen at the same time?
What is the probability of flipping a coin and getting heads, then flipping again and getting tails?
1/2 × 1/2 = 1/4
Flipping two coins – is this independent or dependent?
independent
What do we call the result of a single trial in a probability experiment?
outcome
A student flips a coin 100 times and gets 45 heads. Is this probability theoretical or experimental?
experimental
What is the probability of rolling a 1 or a 2 on a 6-sided die?
1/6 + 1/6 = 2/6 or 1/3
A bag has 3 blue and 2 yellow candies. Without replacing the first candy, what is the probability of drawing two yellow candies in a row?
2/5 × 1/4 = 2/20 or 1/10
Drawing two cards without replacement – independent or dependent?
dependent
What is the term for all possible outcomes of an experiment?
Sample Space
You spin a spinner 20 times and get “blue” 12 times. Based on that, what’s the experimental probability of spinning blue?
12/20 or 3/5
On a spinner with 8 equal sections numbered 1–8, what is the probability of spinning a number less than 4 or an even number?
P(<4) + P(even)
3/8 + 4/8
= 7/8
There's 9 pink balls and 1 green ball in a bag. Two balls are drawn at random, one at a time with replacement. What is the probability of drawing 2 pink balls? Answer in a percentage.
9/10 x 9/10 = 81/100 = 81%
Are rolling a dice then spinning a spinner independent events?
independent
A teacher says a coin is biased. What does that mean?
The coin does not have an equal chance of landing on heads or tails.
Why might experimental probability differ from theoretical probability?
randomness or small sample size
What is the probability of drawing a red card or a queen from a standard deck of 52 cards? (Hint: Don't double-count red queens!)
26/52 + 4/52 – 2/52 = 28/52 or 7/13?
You draw 3 cards from a deck without replacing them. What is the probability all 3 are aces?
4/52 × 3/51 × 2/50 = 24/132600
Why does removing one marble from a bag and not replacing it before drawing again make the events dependent?
Because the total number of outcomes changes for the second draw.
What is a dependent event?
Where the outcome of the 1st event DOES affect the outcomes of other events.
What is the theoretical probability of rolling a one 3 times in a row with a 6-sided dice?
A bag has 3 red, 5 green, and 2 blue marbles. You draw 2 marbles without putting any back. What is the probability of drawing 2 red or 2 blue marbles.
P(B,B) + P(R,R)
P (2/10) x P (1/9) + P (3/10) x P (2/9)
= 2/90 + 6/90
= 8/90 or 4/45
A letter is randomly chosen from the word FOOD. Then one letter is randomly chosen from the word DOG. What is the probability that both letters are the same?
PO (2/4 x 1/3) + PD (1/4) + (1/3)
=2/12 + 1/12
=3/12 = 1/4
You randomly pick 2 students from a class of 25 without replacement. What is the probability that both students are left-handed, assuming 5 are left-handed?
5/25 × 4/24 = 20/600 or 1/30