Question

Given 10 samples with a mean of 29.6 and standard deviation of 1.25. At 95% confidence using the one sided t table, what is the upper limit of the confidence interval.

Answer 1

1.To find Df

Subtracting 1 from sample size gives degrees of freedom,Df=10-9=1

2.To find

Subtract confidence level from 1 and divide by 2

=(1-0.95)/2=0.025

3.Corresponding to values and Df,looking in t distribution table gives value

=2.262

4. Divide Standard deviation by root of sample size and multiply with above value obtained from t distribution table

5.For upper limit,add above value to the mean.

29.6+0.894134=30.494134

30.494134 is the upper limit of the confidence interval.