Question

According to a study of political​ prisoners, the mean duration of imprisonment for 30 prisoners with chronic​ post-traumatic stress disorder​ (PTSD) was 30.8 months. Assuming that o=45 ​months, determine a 90​% confidence interval for the mean duration of​ imprisonment,u​,of all political prisoners with chronic PTSD. Interpret your answer in words.

90% confidence interval is from what % to what %?

Answer 1

Solution :

Given that,

Z/2 = Z_0.05 = 1.645

Margin of error = E = Z/2 * ( /n)

= 1.645 * ( 45 /  30 )

= 13.52

At 90% confidence interval estimate of the population mean is,

  ± E

= 30.8 ± 13.52

= ( 17.28, 44.32 )

We are 90% confident that true mean of all political prisoners with chronic PTSD between 17.28 and 44.32