Need help with probability and statistics

timer Asked: Nov 16th, 2015
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Question Description

From generation to generation, the mean age when smokers first start to smoke varies. However, the standard deviation of that age remains constant at around 2.1 years. A survey of 41 smokers of this generation was done to see if the mean starting age is at least 19. The sample mean was 18.2 with a sample standard deviation of 1.3. Do the data support the claim at the 5% level?   

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Tutor Answer

School: Carnegie Mellon University

Thank you for the opportunity to help you with your question!

null hypothesis=starting age to smoking is 19

alternative hypothesis=starting age is not 19

actual mean is 18.2 and the expected mean is 19. We need to normalize our data since we are assuming normality and we need to find Z statistic to be able to either accept or reject our hypothesis

(18.2-19)/1.3= -0.6154

we need normal tables to check our Z statistic of -0.6154 and make the necessary conclusion.

our result is 0.9463 which is greater than our level of significance of 0.05. we reject the null hypothesis and conclude that the data is not sufficient enough to claim a starting age of 19 to smoking

Please let me know if you need any clarification. I'm always happy to answer your questions.

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