A researcher collated data on Americans’ leisure time activities. She found the mean number of hours spent watching television each weekday to be 2 point 7 hours with a standard deviation of 0 point 4 hours. Jonathan believes that his football team buddies watch less television than the average American. He gathered data from 15 football teammates and found the mean to be 2 point 3 Which of the following shows the correct z -statistic for this situation?
For a sample mean, calculate the z-statistic using the standard error: (sample mean − population mean) ÷ (population standard deviation ÷ √sample size). Substituting the values gives (2.3 − 2.7) ÷ (0.4 ÷ √15) ≈ −3.87. Therefore, the correct choice is “negative 3 point 8 7.”
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