Tree Diagrams
Exp and Theo Probability
Ind and Dep Probability
Mathcounts Probability
Random Review
100
The probability that Avery will hit a target is 1/2. The probability that Alexa will hit a target is 4/5. If each of them fires once, find the probability that the target will be hit by...
a) both of them
b) only one of them
a) P(both) = 40%
b) P(only one) = 50%
100
Find the experimental probability of rolling a 1 or a 4. Write your answer as a percent.
P(1 or 4) = 24%
100
A basket contains five apples and seven peaches. You randomly select one piece of fruit and eat it. Then you randomly select another piece of fruit. Find the probability that the first piece of fruit is an apple and the second piece is a peach. Write your answer as a percent.
P(A then P) = about 26.5%
100
Kima flips a fair nickel twice and will win $2 only if both flips come up tails. What is the probability that Kima will win $2? Express your answer as a percent.
25%
100
The square root of 70 is between which two numbers?
8 and 9
closer to 8
200
A boat has two independent identical propellers. The boat will only move if at least one propeller is working. The probability that a propellor will fail during a trip is 0.05. Find...
a) P(both propellors will fail)
b) P(the boat completes the trip)
a) P(both propellors will fail) = 0.0025
b) P(the boat completes the trip) = 0.9975
200
Contestants randomly draw a ticket from a hat and replace it. The table shows the results after 40 draws. There are 7 winning tickets in the hat. Predict the total number of tickets in the hat.
140
200
A weather forecaster suggests the probability of rain on Saturday is 30%. On Sunday there is a 60% chance of rain. If the forecaster’s probabilities are correct, what is the probability of no rain all weekend? Write your answer as a decimal.
P(no rain) = 0.28
200
Mark and Mary each roll a fair six-sided die simultaneously. The player with the higher number wins the round. If they roll the same number, they roll again until someone wins. What is the probability that Mary wins given that Mark rolls a 2?
2/3
200
Simplify without a calculator.
(1/2)^2 +7/8
1/4 + 7/8
2/8 + 7/8
9/8 or 1 1/8
300
Bryn has 7 baseball cards and 5 football cards. Zoe has 12 baseball cards and 18 football cards. Each of them selects a card at random from her own collection. Find the probability that the two cards selected are one baseball card and one football card.
31/60 or about 52%
300
A bag contains 50 marbles. You randomly draw a marble from the bag, record its color, and then replace it. The table shows the results after 30 draws. Predict the number of red marbles in the bag.
15
300
Consider that 3 consecutive cards are drawn without replacement from a shuffled deck of cards (52 cards in all). What is the probability that all three cards are a King? Write your answer as a percent.
P(3 kings) = about 0.02 percent
300
Blake has three cards–one labeled Y, one labeled T, and one labeled O. He shuffles them and places them face down. He then flips them over one at a time, from left to right. If the cards appear in the order T-O-Y, he wins a toy. What is the probability that Blake wins? Hint: make a sample space.
1/6
300
2 2/3 ÷1 1/2
1 7/9 or 16/9