ITEC 1010 Study Guide - Final Guide: Variance

• School: York University
• Department: Information Technology
• Course: ITEC 1010
• Professor: Marina Erechtchoukova

Document Summary

Let the observed value of the mean and of the sample variance of a randomsample of size 20 from a distribution that is n( , 2) be 81. 2 and 26. 5, respectively. find respectively 90%, 95% and 99% confidence intervals for . Note how thelengths of the confidence intervals increase as the confidence increases. The confidence interval for the population mean, is defined by. Here is the critical value of t at (n 1) degrees of freedom corresponding to level of significance. The critical value of t at (20 1=19) degrees of freedom corresponding to 90% confidence level is 1. 729. The critical value of t at (20 1=19) degrees of freedom corresponding to 95% confidence level is 2. 409. The critical value of t at (20 1=19) degrees of freedom corresponding to 99% confidence level is 2. 861. Then, substitute the values in the confidence interval formula. From the confidence intervals, observe that the length of the interval increases as the confidence level increase.