A sample of 14 commuters in Baltimore showed the average of the commuting times

Question

A sample of 14 commuters in Baltimore showed the average of the commuting times was 33.2 minutes. If the standard deviation was 8.3 minutes find the 95% confidence interval of the true mean. Suppose that the average temperature in July in Tokyo is a normal random variable with parameters mu =90 (measured in degrees Fahrenheit), and sigma = 5. Find the probability that in a given year the average Temperature in June in Baltimore will be (a) above 100 degree F (b) below 95 degree F (c) between 85 degree F and 95 degree F (d) below 88 degree F

Explanation / Answer

1)Standard error = Sigma/sqrt(n) = 8.3/sqrt(14)= 2.2182

z for 95% confidence interval is 1.96

Hence,the 95% confidence interval is (mean-z*standard error, mean+z*standard error) = (33.2-1.96*2.2182, 33.2+1.96*2.2181) = (28.85,37.54)

Please repost second question individually.

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