Question: Age at onset of dementia was determined for a sample of adults between the ages of 60 and 75. For 15 subjects, the results were \(\sum{{{x}_{i}}}=1008\), and \(\sum{x_{i}^{2}}=67,878\). Use this information to answer the following:

a. What is the mean and s for this data? (5 pts.)

b. What is the percentile rank for an individual who shows dementia at age 62? (5 pts)

c. If we consider +/-1z to be the normal range of onset, what ages correspond to this? (5 pts.)

d. What ages identify the most deviant 20%? (5 pts.)