# Confidence interval using Normal Distribution

Not what you're looking for?

Prof. Hardtack gave three exams last semester in a large lecture class. The standard deviation s = 7 was the same on all three exams, and scores were normally distributed. Below are scores for 10 randomly chosen students on each exam. Find the 95 percent confidence interval for the mean score on each exam. Do the confidence intervals overlap? If so, what does this suggest?

Exam 1: 71, 69, 78, 80, 72, 76, 70, 82, 76, 76

Exam 2: 77, 66, 71, 73, 94, 85, 83, 72, 89, 80

Exam 3: 67, 69, 64, 65, 72, 59, 64, 70, 64, 56

##### Purchase this Solution

##### Solution Summary

95 percent confidence interval for the mean score on 3 exams are calculated. It is also determined whether the confidence intervals overlap.

##### Solution Preview

Prof. Hardtack gave three exams last semester in a large lecture class. The standard deviation s = 7 was the same on all three exams, and scores were normally distributed. Below are scores for 10 randomly chosen students on each exam. Find the 95 percent confidence interval for the mean score on each exam. Do the confidence intervals overlap? If so, what does this suggest?

Exam 1: 71, 69, 78, 80, 72, 76, 70, 82, 76, 76

Exam 2: 77, 66, 71, 73, 94, 85, 83, 72, 89, 80

Exam 3: 67, 69, 64, 65, 72, 59, 64, 70, 64, 56

Exam 1

71 69 78 80 72 76 70 82 76 76

Total= 750

n= 10

Mean= 75 =750/10

95% Confidence limits

Mean=M = 75

Standard deviation =s= 7

sample size=n= 10

sx=standard ...

##### Purchase this Solution

##### Free BrainMass Quizzes

##### Know Your Statistical Concepts

Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.

##### Measures of Central Tendency

This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.

##### Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

##### Measures of Central Tendency

Tests knowledge of the three main measures of central tendency, including some simple calculation questions.