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Alg 2 Trig
WORKSHEET #3
Conditional Probability and Multiple Probabilities
Name _______________________
The table below holds information about students’ weather preferences.
Girls
Boys
Likes the cold No preference Does not like the cold
45
70
50
60
30
35
A student is chosen at random. Find each probability.
1. P(boy)
2. P(someone who does not like cold)
3. P(boy, given that they like the cold)
4. P(likes the cold, given that it’s a boy)
5. P(has no preference, given that it’s a girl)
6. P(girl, given that they don’t like the cold)
A die is rolled twice. Find each probability.
7. P(5, then 6)
10. P(any number, then not 5)
8. P(no 2s)
9. P(two 1s)
11. P(4, then not 6)
12. P(not 1, then not 2)
A board game uses a set of 6 different cards. Each card displays one of the following figures: a star, a
square, a circle, a diamond, a rectangle, or a pentagon. The cards are placed face down, and a player
chooses two cards. Find each probability.
13. P(circle, then star), if replacement occurs
occurs
14. P(diamond, then square), if no replacement
15. P(2 four sided figures), if replacement occurs
occurs
16. P(2 four sided figures), if no replacement
There are 3 nickels, 2 dimes, and 5 quarters in a purse. Three coins are randomly selected. Find each
probability.
17. P(nickel, then dime, then quarter), no replacement
replacement
19. P(2 quarters, then 1 nickel), no replacement
18. P(nickel, then dime, then quarter),
20. P(3 dimes), if replacement occurs
21. P(3 dimes), if no replacement occurs
For Exercises 22 and 24, determine whether the events are independent or dependent. Then find each
probability.
22.
Serena is creating a painting. She wants to use 2 more colors. She chooses randomly from 6
shades of red, 10 shades of green, 4 shades of yellow, 4 shades of purple, and 6 shades of blue. What
is the probability that she chooses 2 shades of green?
23.
The 2010-11 Chicago Bulls held their opponents to a 43% shooting percentage. What is the
probability of an opponent missing 2 consecutive shots against the Bulls?
24.
METEOROLOGY The Fadeeva's are planning a 3-day vacation to the mountains. A longrange forecast reports that the probability of rain each day is 10%. Assuming that the daily
probabilities of rain are independent, what is the probability that there is no rain on the first two
days, but that it rains on the third day?