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Course: AP??/College Statistics?>?Unit 9

Lesson 6: Sampling distributions for sample means
Math
AP??/College Statistics
Sampling distributions
Sampling distributions for sample means
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Mean and standard deviation of sample means

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Problem

A light bulb manufacturer claims that a certain type of bulb they make has a mean lifetime of 1000 hours and a standard deviation of 20 hours. Each package sold contains 4 of these bulbs. Suppose that each package represents an
of bulbs, and we calculate the sample mean lifetime x? of the bulbs in each package.
Calculate the mean and standard deviation of the sampling distribution of x?.
μx?=
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
hours
σx?=
  • Your answer should be
  • an integer, like 6
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
  • an exact decimal, like 0.75
  • a multiple of pi, like 12 pi or 2/3 pi
hours