Basic Probability
What is the probability of flipping a coin and getting heads?
1/2
Which is more likely: rolling a 2 on a die or flipping tails on a coin?
Flipping tails (1/2) is more likely than rolling a 2 (1/6).
What is theoretical probability?
Probability based on all possible outcomes.
If the chance of rain is 70%, what is the probability it will not rain?
30% or 0.30
A bag has 3 red marbles and 2 blue marbles. What is the probability of picking a red marble?
3/5
If chance of winning is 1/4 and losing is 1/2, which is more likely?
Losing, 1/2 > 1/4.
What is experimental probability?
Probability based on the actual results of an experiment.
A class has 10 boys and 15 girls. What is the probability of picking a girl?
15/25 = 3/5
What does it mean if an event is "impossible"? Give an example.
Probability 0;
Example: rolling a seven on a six-sided die.
Two events have equal probability. What does this mean?
Both are equally likely to happen
A spinner theoretically lands equally on 4 colors. You spin 40 times and get red 5 times. What’s the experimental probability of red?
5/40= 1/8
What is the probability of picking a heart from a deck of cards?
1/4
A jar contains 4 green, 5 white, and 1 black marble. What is the probability of picking a marble that is not white?
4+1/10= 5/10= 1/2
Which is more likely: picking a heart from a deck or rolling a 6 on a die?
Both have a probability 1/4 (hearts) vs. 1/6 (rolling a 6), so picking a heart is more likely.
You flip a coin 20 times, and you get heads 14 times and tails 6 times. What is the theoretical probability of flipping a coin and getting heads?
A weather forecast says there’s a 40% chance of snow. What is the probability it does not snow?
60% or 0.6
If you toss two coins at the same time, what is the probability that both coins land on heads?
1/2 x 1/2 = 1/4
Event A has probability 3/8 and event B has probability 5/8. Which event is more likely?
Event B is more likely
You flip a coin 20 times, and you get heads 14 times and tails 6 times. What is the experimental probability of flipping a coin and getting heads?
14/20 = 7/10 = 70%
A jar contains 8 red, 6 green, and 6 blue candies. If you pick one candy without looking, what is the probability it’s either green or blue?
6+6/20= 12/20= 3/5