Question 181383
Advertisers need to know which age groups are likely to see their ads. Purchasers of 120 copies of Cosmopolitan are shown by age group. 
(a) Make a bar chart and describe it.
Can't do that on this site.
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(b) What would be the appropriate Null and Alternate Hypotheses?
Ho: p1=p2=p3...=p5
Ha: At least one of the proportions is different
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(c) Calculate expected frequencies for each class.
E = 120/6 = 20
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(d) Perform the chi-square test for a uniform distribution. At α = .01, does this sample contradict the assumption that readership is uniformly distributed among these six age groups? 
test statistic: Chi-Sq = 25.25
critical value: df = 6-1 = 5; alpha=1%; Chi-Sq = 15.086
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Conclusion: Since test stat is greater than critical value, Reject Ho.
At least one of the proportions is different.
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Cheers,
Stan H.
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(See J. Paul Peter and Jerry C. Olson, Consumer Behavior and Marketing Strategy, 9th ed. [McGraw-Hill, 2004], p. 300.) 
Purchaser Age Units Sold
18~24 38
25~34 28
35~44 19
45~54 16
55~64 10
65+ 9
Total 120