Question 1120313: A recent article in The Wall Street Journal entitled” As Identity Theft Moves Online, Crime Rings Mimic Big Business” states that 39% of the consumer scam complaints by American consumers are about identity theft. Suppose a random sample of 90 complaints is obtained. Of these complaints, 40 were regarding identity theft. Based on these sample data, what conclusion should be reached about the statement made in the Wall Street Journal? (Test using (alpha) = 0.10).
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! Ho: p=0.39
Ha: pNE 0.39
alpha=0.10
test statistic is one sample proportion z=phat-p divided by sqrt (p*(1-p)/n)
critical value is |p|>1.645
calculation is z=(0.444-0.39)/sqrt(0.44*0.56/90), exact square root is 4/9*5/9/90 which is 0.0524
z=0.0544/0.0524=1.04
Fail to reject Ho, and there is insufficient evidence to reject the population proportion of 0.39.
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