Author Question: Whenever the population standard deviation is unknown, which distribution is used in developing an ... (Read 79 times)

RODY.ELKHALIL

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Whenever the population standard deviation is unknown, which distribution is used in developing an interval estimate for a population mean?
 a. standard distribution
  b. z distribution
  c. binomial distribution
  d. t distribution

Question 2

The life expectancy of a particular brand of tire is normally distributed with a mean of 40,000 and a standard deviation of 5,000 miles. What is the probability that a randomly selected tire will have a life of exactly 47,500 miles?
 a. .4332
  b. .9332
  c. .0668
  d. 0



triiciiaa

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Answer to Question 1

d

Answer to Question 2

d



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