(a) We would like to estimate the difference between the true mean driving speed
ID: 3128256 • Letter: #
Question
(a) We would like to estimate the difference between the true mean driving speeds of teenagers and seniors. We measure the speeds (in km/h) of a random sample of 20 teenage drivers and 15 senior drivers and calculate a 95% confidence interval for
12
to be (12, 19). Provide an interpretation of this confidence interval.
(b) We conduct a matched pairs t test to determine whether there is evidence that husbands are older than their wives on average. In a random sample of 25 married couples, the husbands were found to be an average of 2.2 years older than their wives. We conduct an appropriate hypothesis test and calculate a P-value of 0.0924. Provide an interpretation of this P-value.
Explanation / Answer
a. One can be 95% confident that the true difference in population mean of speeds among teenage drivers and senior drivers is between 12 K/h and 19Km/h.
b.The p value obtained is not less than alpha=0.05 (standard significance level), thus, fail to reject null hypothesis. This means that there is not sufficient sample evidence to conclude that husbandas are older than their wives on average.
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