According to Runner’s World magazine, the finishing times in 10 kilometer races have a mean of 61 minutes and a standard deviation of 9 minutes. Assume tht these times are normally distributed.
What percentage of individual finishing times are less than 5 minutes? Assume that a random sample of 25 runners is selected and the mean finishing time of the sample is computed. What percentage of sample means are less than 55 minutes?
How do you figure this out?
if you have a graphing calculator go to 2nd vars then normcdf() then type in the mean, standard deviation, lower boundary (which is 0 since you can’t have negative time), and upper boundary which is 55. Each number value should be separated by a comma. That should give you your answer.
February 7th, 2010 at 3:52 am
if you have a graphing calculator go to 2nd vars then normcdf() then type in the mean, standard deviation, lower boundary (which is 0 since you can’t have negative time), and upper boundary which is 55. Each number value should be separated by a comma. That should give you your answer.
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