Review For Probability Test

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Review For Probability Test
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1. Which of the following values cannot be
   probabilities?

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• 2. In the New York State Lottery, you have to
  select six numbers between 1 and 54 inclusive.
  There are 25,827,154 different possible six
  number combinations.
• What are your chances of winning the grand
  prize (all six correct numbers) if you buy
  100,000 tickets each with distinct number
  combinations? Round your answer to 3 decimal
  places.

0.004
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• 3. Assuming that boys and girls are equally
  likely, a couple had four children one at a time.
  The first was a boy the second was a boy the
  third was a boy and the forth was also a boy. Now
  they are expecting their 5th baby. They still
  dont know the sex of the baby but they do know
  that it is not a multiple birth. what is the
  probability that there fifth baby is also a boy?

0.5
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• 4. An American household is chosen at random and
  asked how many cars and trucks that household
  owns. Here are the probabilities as of 1997
• This is a legitimate assignment of probabilities
  because it satisfies these rules
• (a) all the probabilities are between 0 and 1.
• (b) all the probabilities are between -1 and 1.
• (c) the sum of all the probabilities is exactly
  1.
• (d) Both (a) and (c).

D
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5. What is the probability that a randomly chosen
household owns more than one motor vehicle?

• (a) 0.96 (b) 0.71
• (c) 0.26 (d) 0.25

B
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• 6. It is common for public opinion polls to
  have a confidence level of 95, meaning that
  there is a 0.95 probability that the poll results
  are accurate within the claimed margins of error.
  If five different organizations conduct
  independent polls, what is the probability that
  all five of them are accurate within the claimed
  margins of error? (Round to 3 decimals)

0.774
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• 7. For Yorktown students, there are only five
  different restaurants to go for lunch Wendys,
  Bagel Bakery, Taco Bell, Harris Teeter and
  Subway. Each restaurant is independent of each
  other and students can only go one place for
  lunch. The probability of a student going to
  Wendys is 0.27, Bagel Bakery is 0.32, Taco Bell
  is 0.12, and Harris Teeter is 0.08.
• a. What is the probability of a student going to
  Subway for lunch?
• b. What is the probability of a student going to
  a fast food restaurant for lunch? (Wendys or
  Taco Bell)

.21
.39
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• 8. Decide whether events A and B are mutually
  exclusive.
• A- Being left handed
• B - Being female
• A- Rolling a dice and getting a 6
• B Rolling a dice and getting an odd
• number
• A Being born in July
• B - Being born in 1990
• P(A) 4/15 and P(B) 6/15
• P (A or B) 10/15

NO
Yes
NO
Yes
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• 9) A bag contains 15 marbles four are red, five
  are green, six are yellow. (Answer in decimal
  form)
• a. If one marble is randomly selected what is the
  probability that it is not red?
• b. If one is randomly selected, what is the
  probability that it is red or green?
• c. If one is randomly selected, what is the
  probability that it is not blue?

11/15.73
9/15.6
15/151
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4/52.08
26/52.5
16/52.31
36/52.69
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Review Game Rules

• One chance per question!
• In order to get credit for the question, you need
  to show both the set up and the final answer in
  percent or decimal form!
• First correct Answer gets 2
• Second correct Answer gets 1
• Answers need to be presented on the white boards!

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• 11.
• I What is the probability of rolling two dice and
  getting a total of six?
• II. What is the probability of getting a total of
  seven?
• III. What is the probability of getting a total
  of 2 or three?

C
D
A
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12. Six cards are randomly drawn from a standard
deck without replacement. What is the probability
that at least one of them is a club?Decimal
Answer
1-(39/52)(38/51)(37/50)(36/49)(35/48)(34/47).84
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• 13. Four firms using the same auditor
  independently and randomly select a month in
  which to conduct their annual audits. What is the
  probability that the months are the same for all
  four auditors?
• Decimal Answer

(12/12)(1/12)(1/12)(1/12).00058
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• 14. Ten percent of us are left handed. What is
  the probability that 8 randomly selected people
  will all be right handed?
• Decimal Answer

(.9)8.43
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• 15. True or False? If you were to roll a fair
  dice 1,000 times, the proportion of sixs rolled
  will be a lot closer to 0.17 than if you were to
  do it only 5 times.

TRUE!!!!
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• 16. A classic excuse for a missed test is
  offered by four students who claim that their car
  had a flat tire. On the makeup test, the
  instructor asks the students to identify the
  particular tire that went flat. If they really
  didnt have a flat tire and randomly select one
  that supposedly went flat, what is the
  probability that they will all select the same
  tire? Decimal Answer

(4/4)(1/4)(1/4)(1/4).016
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• 17. If a couple plans to have eight children,
  find the probability that they have at least one
  boy.
• Decimal Answer

1-(1/2)8.996
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• 18. What is the probability that no two people
  have the same birthday when the number of
  randomly selected people is 4????
• Decimal Answer

(365/365)(364/365)(363/365)(362/365).984
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• 19. An employee needs to call any one of five
  colleagues. Assume that the five colleagues are
  random selections from a population in which 28
  have unlisted numbers. Find the probability that
  at least one of the five fellow workers will have
  a listed number.
• Decimal Answer

1-(.28)5.998
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• 20. There is a 0.63 probability that Mobil
  stock will rise, a 0.75 probability that Gulf
  stock will rise, and a 0.47 chance that both
  stocks will rise. Find the probability that
  neither stock will rise.

.2775
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• 21. A typing pool is made up of five men and
  five women. If three different typists are
  randomly selected from the pool, find the
  probability that at least one of the three is a
  man. Decimal Answer

1-(5/10)(4/9)(3/8).92