Suppose we are contracted by the
Justice Department to study the extent of juvenile
delinquency. We take a random sample of 100 juveniles, and we
find that the mean number of crimes committed is 12 with a standard
deviation of 7.
1. Construct a 95% confidence interval for the mean number
of crimes committed by the population of juveniles.
2. Interpret the meaning of this interval.
3. Test the null hypothesis that the mean number of crimes
committed by the population of juveniles is less than or equal to
11. Use a significance level of .05.
4. If you rejected the null hypothesis, explain why.
If you failed to reject the null hypothesis, explain why. (Be
sure to use the concept of probability in your answer).