The Bureau of Labor Statistics reported that the average yearly ...

[wenmo]

The Bureau of Labor Statistics reported that the average yearly income of dentists in the year 2012 was 110,000 . A sample of 81 dentists, which was taken in 2013, showed an average yearly income of 120,000 . Assume the standard deviation of the population of dentists's incomes in 2012 is 36,000.
 a. We want to test and determine if there has been a significant increase in the average yearly income of dentists. Provide the null and the alternative hypotheses.
  b. Compute the test statistic.
  c. Determine the p-value; and at a 5 level of significance, test the hypotheses.

Question 2

A description of how the probabilities are distributed over the values the random variable can assume is called a(n) _____.
 a. probability distribution
  b. probability function
  c. random variable
  d. expected value

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Answer to Question 1

a. H0:   110,000
Ha:  > 110,000
b. z = 2.5
c. p-value = .0062
Since the p-value = .0062 < .05, reject H0 . Therefore, it can be concluded that there has been a significant increase.

Answer to Question 2

a