Question

For Problem 1 and 2: A random sample of 16 graduates of a certain secretarial school typed an average of 85 words per minute with a standard deviation of 8 words per minute. Assume that the number of words typed per minute of a randomly selected graduates follows a normal distribution 1. (4 pts) a 95% confidence interval to estimate the average number of words typed by all graduates of this school. Remember to state the assumptions and interpret the result. Following R commands may be helpful. qnorm(.9) = 1.28 qnorm(.95)-1.68 qnorm(.975)-1.96 qt (0.9, df-15) -1.34 qt (0.95, df=15) 1.75 qt(0.975, df-15) -2.13 2. (1 pt) Based on the interval from Problem 1, is it plausible that population mean typing speed of students in this secretarial school is 80 words per minute? Explain.

Answer 1

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