Question

With 90% confidence, for sample mean 391.50, sample standard deviation 13.40, and sample size 35, what is the upper confidence limit with 2 decimal places?

What is the critical value for 95% confidence level is a hint to this question.

Answer 1

Given 391.5 13.4 35 90 % Confidence Interval is = X 202*svn α 0.10 Critical Value 20/2 = -1.644854 = 1.645 Lower limit = 7 - Zuz*svn =391.5 -1.645*13.4135 = 387.7741 Upper limit = x + z2*svn =391.5 +1.645*13.4735 = 395.2259 Upper limit for this confidence interval is = 395.23

95 % Confidence Interval is = x 2,*svn a = 0.05 Critical Value Zu/2 = -1.959964 = 1.96 Lower limit = t - Zu2*sVn =391.5-1.96*13.4735 = 387.0606 Upper limit = * + Z02*svn =391.5 +1.96*13.4735 = 395.9394 95 % Confidence interval is =(387.06, 395.94)