7. show that each of the following families of distributions is a two-parameter exponential family as defined in exercise 6: a. the family of all normal distributions for which both the mean and the variance are unknown b. the family of all gamma distributions for which both α and β are unknown c. the family of all beta distributions for which both α and β are unknown

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.