statistics
posted by Anonymous .
A study of 36 marathon runners showed that they could run at an average rate of 7.8 miles per hour. The sample standard deviation is 0.6. Find a point estimate of the population mean. Find the 90% confidence interval forthe mean of all runners. Based on the results, what minimum speed should a runner obtain to qualify to run in a marathon? answer

Z = (scoremean)/SEm
SEm = SD/√n
90% = mean ± 1.645 SEm
What is your cutoff point to run?