Question

You have an SRS of 15 observations from a Normally distributed population. What critical value would you use to obtain a 98% confidence interval for the mean μ of the population?


I know the answer is 2.602...but I do not understand why


Tell me if I'm wrong:
n=15 therefore the df = 14 (n-1)
Area = .98

So I plugged this into the inverse T:
area: .98
df: 14
Inverse = 2.26 (but this is not the right critical value)

Can someone guide me through the steps please...and i know there is a chart you can use but i want to figure it out on my Ti-89 because that's what we use for the exam

Answer 1

n=15 therefore the df=14 (n-1)
Area=0.01 1-0.98=0.02 --> 0.02/2=0.01

invT(0.01,14)= -2.62