18. A professor in the women’s studies program believes that the amount of smoking by women has increased in recent years. A complete census taken 2 years ago of women living in a neighboring city showed that the mean number of cigarettes smoked daily by the women was 5.4 with a standard deviation of 2.5. To assess her belief, the professor determined the daily smoking rate of a random sample of 200 women currently living in that city. The data show that the number of cigarettes smoked daily by the 200 women has a mean of 6.1 and a standard deviation of 2.7.

a. Is the professor’s belief correct? Assume a directional H1 is appropriate and use   0.051 tail in making your decision. Be sure that the most sensitive test is used to analyze the data.

b. Assume the population mean is unknown and reanalyze the data using the same alpha level.

What is your conclusion this time?

c. Explain any differences between part a and part b.

d. Determine the size of the effect found in part b.

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