In: Statistics and Probability
Independent random samples of times served for 10 released prisoners for fraud offense showed a mean of 10.12 months and a standard deviation of 4.90 months whereas times served for 10 released prisoners for firearms offense showed a mean of 18.78 months and a standard deviation of 4.64 months. a) At = 0.05, do the data suggest that mean time served for fraud is less than that of firearm offenses? Assume that times are normally distributed in both groups and have same variances. (Use the critical value approach and the P-value approach) b) Find a 90% confidence interval for the difference between the mean times served by prisoners in the fraud and firearms offense categories. c) Use the Mann-Whitney test at = 0.05 using the data below: Fraud: 3.6 5.3 10.7 8.5 11.8 17.9 5.9 7.0 13.9 16.6 Firearms: 25.5 10.4 18.4 19.6 20.9 23.8 17.9 21.9 13.3 16.1