In: Statistics and Probability
After collecting a sample of 250 elements from a population with
a
known standard deviation of 13.7, the mean is found to be
112.4.
a) Find a 95% confidence interval for the mean.
b) Find a 99% confidence interval for the mean.
2. Jon Jackobson, a very dedicated graduate graduate, has just
completed a first
700 page version of his thesis. Jon typed the job himself and
he's
interested in knowing the average number of typographical errors
per page, but not
wants to read the entire document. Since he knows somethings about
statistics for
Administration, Jon read 40 randomly selected pages and found that
the
average typographical errors per page was 4.3 and the standard
deviation of the
Sample was 1.2 errors per page.
a) Calculate the estimated standard error of the mean.
b) Calculate a 90% confidence interval for the true average
number
errors per page