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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

Ask the Professor Forum

Hi Professor,

Question on Homework Problem number 14 under section 5.3. When I solve for the z-score I get -3.04 but then the I get stuck because I am not getting the right answer.

Among women aged 15 to 44, average age at first sexual intercourse was 17.3 years. Their male
counterparts lost their virginity at 17.0 years on average both groups had a standard deviation of
2.17 years. What is the probability that a randomly chosen group of 36 females lost their virginity
at an age under 16.2 years old?

Thank you.

Posted to STATS 1 on Friday, November 8, 2013   Replies: 1

Professor Mcguckian
10:42 AM EST

Hi Natalie,

If you found the correct z-score of -3.04, I am not sure why the rest of the problem would give you any difficulty. However, I created a video to show how the entire problem is done. Watch it to look for your error.

Professor McGuckian


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