Tree Diagrams
Exp and Theo Probability
Ind and Dep Probability
Mathcounts Probability
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%
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
Trevor has four times as many shirts as pants, and he can use them to make 100 different shirt-and-pants outfits. How many pants does Trevor have?
5
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
In how many ways can the letters A, B, C, and D be arranged so that no letter is adjacent to any letter that comes immediately before it or immediately after it alphabetically?
2