To estimate the

Question

mean score � of those who took the Medical College Admission
Test on your campus, you will obtain the scores of an
SRS of students. From published information you know that
the scores are approximately Normal with standard deviation
about 6.4. You want your sample mean xbar to estimate mu � with
an error of no more than 1 point in either direction.
(a) What standard deviation must x have so that 99.7% of all
samples give an xbar within 1 point of mu �? (Use the 68–95–99.7
rule.)
(b) How large an SRS do you need in order to reduce the
standard deviation of xbar to the value you found in part (a)?

Answer 1

Must have 0.3333

Answer 2

m,kj