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#1 2007-01-11 00:50:44

jarnism
Member
Registered: 2007-01-11
Posts: 1

I need some serious help/miracle with this statistics/math problems

Basically I got really scrweed over last quarter. I turned in my take home part of an exam to someone in my teachers department and she never got it. I ended up not getting a final grade but she's letting me redo it with slightly easier problems but they are due in 6 hours or so.

Problem 1
Time magazine recently polled 500 13-year-olds online to get a glimpse into their world. The results may surprise many people: 13-year-olds in 2005 enjoy their relationships with their parents, are less likely to drink or do drugs than previous generations, and they are highly focused, competitive and determined to succeed. The overscheduled toddlers of the 1990s are now controlling their own schedules, and in many cases, their days are just as jam-packed as ever. It seems today's teens are not only used to being extremely busy, they thrive on it. One result from time poll was that 53% of the 13 year olds polled said their parents are very involved in their lives. Suppose that 200 of the 13-year-olds were boys and 300 of them were girls. We wish to find out if the proportion of 13-year-old boys and girls who say that their parents are very involved in their lives are the same.

a) Using symbols, state appropriate null and alternative hypothesis to test the proportions for 13-year-old boys versus 13-yr-old girls.

b) In the sample, 93 boys and 172 girls said that their parents are very involved in their lives. Use this sample information to calculate an appropriate test statistics for testing of the hypothesis state in part a). Show work!


c) For α=0.02, what is z*?

d) What is the p-value for this test?


e) Summarize your conclusion in the context of the problem using α=0.01

f) True or False: The probability that you have made a Type I error is equal to 1%


g) True or False: The probability that you made a type II error is equal to 1-0.01=.0.99

Problem 2
A sample of 19 female bears was measured for chest girth (y) and neck girth (x), both in inches. The LS regression equation related the two variables is ŷ=5.32+1.53x
SSE=231.72 sq. inches, r=0.887, SSxx=365.18 sq.inches, and x¯ =18.76 inches

a) give a practical interpretation of the slope of regression equation, in the context problem

b) Is there a practical interpretation of the intercept for this problem? Explain?


c) What is a 90% prediction interval for the chest girth of a bear with a neck girth of 20 inches?
d) Interpret the 90% PI calculated in part c) in the context of the problem

e) Is estimated slope value of 1.53 statistically significantly greater than zero? Conduct appropriate hypotheses, calculate an appropriate test statistic, calculate a p-value or critical value and interpret your result in the context of the problem. Use α=0.05.


f) How much variation in the chest girth can be explained by knowing neck girth?

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