The standard deviations s for the annual medical costs 30 heart disease patients was found to equal $1005. Find a 95 % confidence interval for the standard deviation of the annual medical costs for all heart disease patients.

Answer 1

N=30

http://www.milefoot.com/math/stat/ci-variances.htm

Answer 2

One hundred subjects in a psychological study had a mean of 35 on a test instrument designed to measure anger. The study the ó=10. Find a 99% confidence interval for the mean anger score of the population.

Answer 3

95% = mean ± 1.96 SEm

99% = mean ± 2.575 SEm

SEm = SD/√n

Answer 4

what is n