. Question 22 v In the past, the mean age of students at a summer camp was 17.5 years old. A recent sample of 18 students from the camp 'Found E = 12.5, 3 = 2.6. a. Build a 80% CI for the current mean age of students at the camp. Round all intermediate calculations to two decimals, then construct the Cl and enter like this: (min,max}. Be sure to use parentheses or you will be marked wrong. Note: if you use a built-in Cl command on a calculatorrcomputer, you might get marked wrong clue to rounding. Use the formulas given in the textfnotes. b. Use your CI to decide whether the mean age of students at the camp has changed from 17.5 years old. C' No, the mean has not changed since the old value of ,u is right in the middle of the new CI "3:3" Yes, the mean has probably changed since the new CI does not contain the old value of JM. '3 Yes, the mean has probably changed since the old value of ,u is not right in the middle of the new CI No, the mean has probably not changed since the new Cl contains the old value of ,u. c. For this problem, it is important that we know that ages are normally distributed. This is because: "3:3" we are using a Z-interval "I." we are using 3 in place of a" '15:? n