Enjoy learning Statistics Online! Please be sure to share and subscribe to our YouTube channel.

ASK THE PROFESSOR FORUM

Course Documents

Chapter 1 - Intro

Chapter 2 - Methods for Describing Sets of Data

Chapter 3 - Probability

Chapter 4 - Discrete Random Variables

Chapter 5 - Normal Random Variables

Chapter 6 - Sampling Distributions

Chapter 7 - Confidence Intervals

Chapter 8 - Tests of Hypothesis: One Sample

Chapter 9 - Confidence Intervals and Hypothesis Tests: Two Samples

Sample Exam I: Chapters 1 & 2

Sample Exam II: Chapters 3 & 4

Sample Exam III: Chapters 5 & 6

Sample Exam IV: Chapters 7 & 8

Problem 3

9.1 Z-Interval to Compare Two Population Means: Independent Samples

A researcher theorized that average heights of boys and girls of the same age prior to undergoing puberty should be the same.  Fifty-eight randomly selected boys of age 8 had an average height of 123.5 cm with a variance of 98cm.  Fifty-five randomly selected girls had an average height of 126.1 cm with a variance of 119cm.  Find the 99% confidence interval for the true mean difference between boys and girls heights at age 8. Is there a significant difference?

« back