Basic Probability
What is the probability of rolling a 3 on a standard six-sided die?
1/6
If you roll a die and flip a coin, what is the probability of rolling a 4 and getting heads?
1/12
If a weather forecast says there is a 70% chance of rain, what is the probability that it will not rain?
30% or 0.3
If you flip a coin, what is the probability of getting tails?
1/2
A box has 5 chocolate bars and 3 fruit bars. If you randomly select 2 bars without replacement, what is the probability that both are chocolate?
5/8 × 4/7 = 20/56 or 5/14
If you have a 1 in 10 chance of winning a raffle, what is the probability of losing?
9/10
A bag contains 3 red balls and 2 blue balls. What is the probability of randomly selecting a red ball?
3/5
If you draw a card from a standard deck of cards, what is the probability of drawing a heart or a queen?
13/52 + 4/52 - 1/52 = 16/52 or 4/13
A survey shows that 60% of students prefer pizza over burgers. If you randomly talk to 5 students, what is the probability that at least one of them prefers burgers?
1 - (0.6^5) = 1 - 0.07776 = 0.92224 or approximately 92.2%
You have a spinner divided into 4 equal parts: Red, Blue, Green, and Yellow. What is the probability of landing on Blue?
1/4
In a class of 30 students, 18 are girls and 12 are boys. If you randomly select 2 students, what is the probability that both are boys?
12/30 × 11/29 = 132/870 or 22/145
A factory produces 1000 toys, and 5% are defective. If you randomly select 3 toys, what is the probability that at least one is defective?
1 - (0.95^3) = 1 - 0.857375 = 0.142625 or approximately 14.3%