posted by anonymous on .
a score of 10 indicates severe depression, while a score of 0 indicates no depression. From reports, she is able to find out about past testing. Fourth graders at her school usually score 5 on the scale, but the variation is not known. Her sample of 20 fiftsh graders has a mean depression score of 4.4.
The counselor calculates the unbiased estimate of the population's variance to be 15. What is the variance of the distribution of means?