Unformatted text preview: Practice Test 3C 1. What is meant by the term joint probability? 2. Lets say a household is prosperous if its income exceeds $75,000. Lets say a household is educated if the household completed college. Select an American household at random, and let A be the event that the selected household is prosperous and let B be the event that is educated. According to the census bureau, P(A)=.15, P(B)=.25, and the probability that the household is both prosperous and educated P(A and B)= .09. What is the probability that the household will be prosperous, given that it is educated? 3. Three cards are dealt. What is the probability that at least one of them will be a heart? 4. There is a fishbowl with fish in it. 14 are goldfish, 6 are angel first, and 10 are guppies. What is the probability of fishing out two fish and having the first one being a goldfish or the second one being an angel fish? (they are fished out without replacement). 5. A bucket contains three red balls and four black balls. What is the probability of picking all three of the red balls (without replacement and with three draws from the bucket.)? 6. Continuing with the above problem. If seven balls are picked, what is the probability that the last one picked will be black? 7. Is the answer to question 6 a joint probability, a composite probability, a marginal probability, or a conditional probability? 8. Two coins are flipped and it is noted where they come up heads or tails. What is the sample space? 9. A deck of cards is well shuffled. What is the probability that the top card is a spade or the bottom card is a club? 10. A deck of cards is well shuffled. What is the probability that the top card is a spade of the bottom card is a king? 11. Can two events be mutually exclusive if they are not independent? 12. For a population of monkeys, there is a disease called Monkeyitis. Ten percent of the population has Monkeyitis. A monkey has it if (and only if) he eats a toxic banana and has a gene for this disease. The probability of eating good bananas is 75%. What is the probability of eating a toxic banana and not getting Monkeyitis. Show work. 13. There are 128 people. 42 women voted “NO” and 14 women voted “Yes”. 54 men voted “no” and 18 men voted “yes”. If event A is picking women and event B is picking someone who said “yes” are events a and b independent? 14. A vase has ten ping pong balls in it. Three are green, two are yellow, and five are red. Two ping pong balls are drawn without replacement. If you can tell me the probability that the second one isn’t yellow given that the first one isn’t green, you are very clever. There are two ways to solve this. 15. E1= {5.7.9}; E2= {9,10,11,12} What is E1 ∩ E2? What is E1∪ E2? 16. Fannie and Gary are thinking about taking Econ 15A. Gary will only take it if Fannie does. The chance that Fannie will take it is 35%. The chance that Gary will take it is 22%. What is the chance that either Fannie or Gary will take Econ 15? 17. Continuing from the above problem, what is the probability that both Fannie and Gary will take the class? 18. An experiment consists of flipping a coin four times. Enumerate all the elementary events. ...
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 Fall '10
 RajendraM.Patel
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