Question: What is the percentage of the total area under the normal curve within plus and minus three standard deviations of the mean?

a. A recent survey reported that 56% of registered voters in Michigan are Democrats.” Does this statement illustrate percentage, proportion or probability?

b. Find the probability for P(-2. 10 < z <2.54).

c. It is known that college students sleep an average of 6 hours per night with a standard deviation equal to 1.8 hours. A student is selected at random. Find the probability that he/she sleeps less than 5 hours

d. Consider a binominal distribution with 15 identical trails, and probability of success of 0.5

I. Find the probability that x=2 using the binomial tables

II. Use the normal approximation to find the probability that x=2