1: Early-Onset Dementia. Dementia is the loss of the intellectual and social abilities severe enough to interfere with judgment, behavior, and daily functioning. Alzheimer's disease is the most com-mon type of dementia. In the article "Living with Early Onset De-mentia: Exploring the Experience and Developing Evidence-Based Guidelines for Practice" (Alzheimer's Care Quarterly, Vol.5, Issue2, pp. 111-122), P. Harris and J. Keady explored the experience and struggles of people diagnosed with dementia and their families. A simple random sample of 21 people with early-onset dementia gave the following data on age at diagnosis, in years. 60 58 52 58 59 58 51 61 54 59 55 53 44 46 47 42 56 57 49 41 43 At the 1% significance level, do the data provide sufficient evidence to conclude that the mean age at diagnosis of all people with early-onset dementia is less than 55 years old? Assume that the population standard deviation is 6.8 years. (Note: x = 52.5 years.)

2: Consider a one-mean z-test. Denote z0 as the observed value of the test statistic z. If the test is right tailed, then the P-value can be expressed as P(z z0). Determine the corresponding expression for the P-value if the test is

a. left tailed.

b. two tailed.

3: The symbol(z) is often used to denote the area under the stan-dard normal curve that lies to the left of a specified value of z. Con-sider a one-mean z-test. Denote z0 as the observed value of the test statistic z. Express the P-value of the hypothesis test in terms of if the test is

a. left tailed.

b. right tailed.

c. two tailed.