03:44
Intro Stats / AP Statistics
(1 point) To estimate the mean height μμ of male
students on your campus, you will measure an SRS of students. You
know from government data that heights of young men are
approximately Normal with standard deviation about 2.8 inches. You
want your sample mean x⎯⎯⎯x¯ to
estimate μμ with an error of no more than one-half inch
in either direction.
(a) What standard deviation must x⎯⎯⎯x¯ have so that
99.7% of all samples give an x⎯⎯⎯x¯ within one-half inch
of μμ? (Use the 68-95-99.7 rule.)
(b) How large an SRS do you need to reduce the standard deviation
of x⎯⎯⎯x¯ to the value you found in part(a)?