Problem #6: An observational study of Alzheimer's disease (AD) obtained data from 16 AD patients exhibiting moderate dementia and selected a group of 9 control individuals without AD. AD is a progressive neurodegenerative disease of the elderly and advancing age is known to be a primary risk factor in AD diagnosis. Therefore, it was crucial for the study's credibility to examine whether the ages in the AD group might be significantly different than in the control group. The ages of the subjects in years are summarized in the R Output below. Variable Alzheimers 16 79.76 Control n Mean sd Minimum 9 6.50 68.33 12.93 77.00 54.00 Q1 Median Q3 Maximum 79.25 87.00 92.25 93.00 56.00 65.00 82.00 89.00 We want to test if the average age in the Alzheimer's group is significantly different than the control group. (a) What is the null hypothesis? (b) Find the value of the test statistic. (c) Find the 5% critical value. (d) What is the conclusion of the hypothesis test? (A) Ho (B) Ho: