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Acc Math 1
Unit 4
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Date
Per
Probability of independent events A and B:
(when items are replaced)
P(A and B) = P(A)  P(B)
Probability of dependent events A and B:
(when items are not replaced)
P(A and B) = P(A)  P(B after A)
Assume all events described in the problems below are independent.
1. Sam makes 70% of his free throws. What is the probability that:
a) Sam makes 2 free throws in a row?
b) Sam makes his first free throw and then misses his next free throw?
c) Sam misses his first free throw and then makes his next?
d) Sam misses both free throws?
2. If you roll a die, the probability that you land on a “one” is 1/6. If you roll the same die
twice, what is the probability that:
a) You land on two “ones” in a row?
b) You never land on a “one”?
3. A sack contains 7 blue, 3 red, and 2 green marbles. If you draw a marble, replace it, and
then draw another marble, what is the probability that:
a) You draw a red marble and then a green marble?
b) You draw a red marble and then another red marble?
c) You draw at least one blue marble?
d) You draw at least one red or blue marble?
e) You never draw a blue marble?
f) Which is more likely to occur and why-- to draw the marble colors RBBR or
to draw the marble colors BBGRBB?
Determine if the events are dependent or independent.
4. choosing a tie and shirt from the closet
5. choosing a month and tossing a coin
6. rolling two fair number cubes once, then rolling them again if you received the same
number on both number cubes on the first roll
An experiment consists of rolling a fair number cube and tossing a fair coin.
7. Find the probability of getting a 5 on the number cube and tails on the dime.
8. Find the probability of getting an even number on the number cube and heads on the
dime.
9. Find the probability of getting a 2 or 3 on the number cube and heads on the dime.
A box contains 3 red marbles, 6 blue marbles, and 1 white marble. The marbles are
selected at random, one at a time, and are not replaced. Find the probability.
10. P(blue and red)
11. P(white and blue)
12. P(red and white)
13. P(red and white and blue)
14. P(red and red and blue)
15. P(red and blue and blue)
16. P(red and red and red)
17. P(white and blue and blue)
18. P(white and red and white)
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