AP Statistics

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AP Statistics

• Sample Means and Proportions Scavenger Hunt Review

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Directions

• Print slides and mount on the walls in your room,
  but in a random order.
• Assign students to start on a different problem.
• Answer to previous problem is at top of the next
  slide.

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0.0423

• Suppose that 47 of all adult women think they do
  not get enough time for themselves. An opinion
  poll interview 1025 women and records the sample
  proportion. Describe the distribution and find
  the mean and standard deviation of the sample.

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Approx Normal mean 0.47,std dev 0.016

• The mean monthly fee that households pay service
  providers for Internet access is 28 with a
  standard deviation of 10, but the distribution
  is not normal. A sample survey asks a SRS of 500
  households with Internet access how much they
  pay. What is the probability that the average
  fee paid by the sample households exceeds 29?

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0.0126

• A mail order company advertises that it ships 90
  of its orders within 3 working days. You select
  a SRS size 100 of the 500 orders received in the
  past week for an audit. The audit shows 86 of
  these orders were shipped on time. What is the
  probability that 86 or fewer in a SRS of 100 are
  shipped on time?

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0.0912

• The average age of cars owned by residents of a
  small city is 4 years with a standard deviation
  of 2.2 years. A SRS of 400 cars is selected, and
  the sample mean age computed. Describe the
  distribution, the mean and standard deviation of
  the sample mean.

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Approx normal with mean 4, std dev 0.11

• A SRS of 100 Americans found that 61 were
  satisfied with service provided by the dealer
  from which they bought their car. Describe the
  distribution, mean, and standard deviation of the
  sample.

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Approx normal withmean 0.61, std dev 0.049

• The incomes in a certain large population of
  college teachers have a normal distribution with
  mean 35,000 and standard deviation 5000. Four
  teachers are selected at random from this
  population to serve on a salary review committee.
  What is the probability that their average
  salary exceeds 40,000?

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0.0228

• The strength of paper coming from a manufacturing
  plant is known to be 25 pounds/square inch with a
  standard deviation of 2.3. In a random sample of
  40 pieces of paper, what is the probability that
  the mean strength is between 24.5 and 25.5
  pounds/square inch?

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0.8351

• A promoter knows that 23 of males enjoy watching
  boxing matches. In a random sample of 125 men,
  what is the distribution, mean and standard
  deviation of the sample?

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Approx normal withmean 0.23, std dev 0.38

• A promoter knows that only 12 of females enjoy
  watching boxing matches. In a random sample of
  125 women, what is the probability that more than
  10 of the females enjoy watching boxing matches?

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0.7548

• The average number of missed school days for
  students in public schools is 8.5 with a standard
  deviation of 4.1. In a sample of 200 public
  school students, what is the probability that the
  average number of days missed is less than 8 days?

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Answers

• Adult women time for themselves
• Approx normal, µ .47, s .016
• Np 1025.47 481.75
• Nq 1025 .53 543.25
• Internet access fees
• Approx normal with µ 28, s 0.447
• P(x-bar gt 29) 0.0126

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Answers

• Mail order company
• Approx normal with µ .9, s .03
• Np .9 100 90, nq .1 100 10
• P(p-hat .86) 0.0912
• Age of cars
• Approx normal, mean 4, std dev 0.11

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Answers

• Car Dealership service
• Approx normal with mean 0.61, std dev 0.049
• Np 61, nq 39
• College teacher incomes
• P(x-bar 40,000) 0.228 with std dev 2500

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Answers

• Paper strength
• Std dev .36
• P(24.5 x bar 25.5) .8351
• Males boxing matches
• Approx normal with mean .23, std dev 0.38
• Np .23 125 28.75
• Nq .77 125 96.25

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Answers

• Females boxing matches
• Approx normal with mean .12, std dev .029
• Np 125 .12 15
• Nq 125 .88 110
• P(phat 0.1) .7548
• Missed school days
• Std dev .29
• P(x-bar lt 8) .0423