Back to the basics
A normal die is rolled. What is the probability of rolling a prime number? P(prime)
1/2
The Scenario: You are flipping a single fair coin two times.
Create a list showing all the possible outcomes.
What is the probability of the coin landing on "Heads" two times?
HT, HH, TH, TT
1/4
You roll two dice numbered 1-6. What is the probability you roll a 3, and then roll a 6? P(3 then 6)
1/36
The Scenario: A bag contains 10 candies. You reach in, grab one, record the color, and put it back. You do this 5 times and get a Blue candy 3 times.
Based on this small sample, if you were to pull a candy 100 times, how many times would you predict you’ll pull a Blue one?
Blue candy 60 times.
If a fair coin is tossed three times, what is the probability of getting tails three times in a row? P(three tails)
1/8
A normal die is rolled. What is the probability of rolling a 4 or a 5? P(4 or 5)
1/3
The Scenario: You have a spinner divided into three equal sections labeled Red, Blue, and Green. You spin the spinner once and flip a coin once.
Create a tree diagram to show all the possible combinations of a color and a coin side.
How many total outcomes are in your sample space? What is the probability of spinning "Red" and flipping "Tails"?
Check Tree Diagrams
1/3 x 1/2 = 1/6
A normal die is rolled and a spinner labeled A - E is spun. Find the probability. P(an odd number and a consonant)
9/30 = 3/10
A factory tests a random sample of 40 flashlights and finds that 2 of them are defective.
If the factory produces 1,000 flashlights today, predict how many will be defective.
50 defective flashlights
You draw a card from a standard deck of cards. What is the probability that the first card will be a heart, and is NOT replaced, the second card is a diamond? P(heart, then diamond)
169/2652=13/204
A normal die is rolled. What is the probability of not rolling a 1 or a 2? P(not 1 or 2)
2/3
The scenario: You roll two standard six-sided dice (number cubes) at the same time.
Create a table where the rows represent the first die (1–6) and the columns represent the second die (1–6).
Using your table, find the probability that the sum of the two dice is exactly 7.
Check Tables
6/36 = 1/6
What is the probability of a teacher choosing all answers as C's on a five questions multiple choice quiz with three choices: A, B, and C?
1/243
The Scenario: You have a spinner with 8 equal sections numbered 1 through 8. You plan to spin it 160 times.
Theoretically, how many times should the spinner land on a number greater than 5?
number greater than five 60 times.
Colt's clothes closet contains 3 blue shirts, 10 white shirts, and 7 striped shirts. What is the probability that Colt will reach in and randomly select a white shirt, not put it back, followed by a striped shirt? P(white, then striped)
70/380 = 7/38
There are 1 red marble, 2 orange marbles, 3 yellow marbles, and 4 green marbles in a bag. Suppose one marble is selected. What is the probability of selecting an orange marble? Express as a percent!!!!! P(orange)
20%
The Scenario: The cafeteria offers a "Main, Side, and Drink" combo.
Main: Pizza or Burger. Side: Fries, Apple, or Salad.
Drink: Milk or Juice.
Create a tree diagram to represent every possible lunch combination.
If a student chooses a meal at random, what is the probability they end up with a meal that includes an Apple?
Check Tree Diagram
4/12 = 1/3
Each time a baby is born, the chance for either a boy or a girl is one-half. Find the probability that a family of five children has five girls. P(five girls)
1/32
The Scenario: A scientist is trying to estimate the number of fish in a small pond. She catches 20 fish, tags them with a yellow sticker, and releases them. A week later, she catches 50 fish and notices that 4 of them have yellow stickers.
Based on the ratio of tagged fish in her second catch, estimate the total population of fish in the pond.
250 fish in the pond.
Two red counters and two white counters are placed in a bag. What is the probability of pulling a red counter, followed by a red counter without replacement? P(red, then red)
2/12= 1/6
Use a standard deck of cards. What is the probability of not pulling out a 5? Express as a fraction.
48/52 = 12/13.
The Scenario: A bag contains 3 marbles: one Red (R), one Blue (B), and one Green (G). You pick one marble, keep it out of the bag, and then pick a second marble.
Create an organized list of all possible pairs of marbles you could pick. (Hint: You cannot pick the same marble twice!)
What is the probability that the color Green is one of the two marbles you selected?
All outcomes: (R, B), (R, G), (B, R), (B, G), (G, R), (G, B)
Green outcomes: (R, G), (B, G), (G, R), (G, B)
4/6 = 2/3
In some versions of the board game Monopoly, your piece is sent to Gaol if you roll three doubles in a row. What is the probability of rolling three doubles in a row? P(three doubles)
What is 1/216?
The Scenario: A basketball player makes 12 shots and misses 3 free throws during practice. Tomorrow, she expects to take 25 free throws during a game.
Predict how many free throws she will make in the game?
20 shots made
Two cards are drawn from a standard deck of cards. Once a card is selected, it is NOT returned. What is the probability of drawing two picture cards in a row? (K,Q,J)
132/2652 = 11/221