12. Calculate the standard deviation of (-14X)
13a. If the probability is .3 that a student passes all his classes, what is the probability that out of 19 students fewer than 8 pass all their classes?
13b. Would it be unusual to see 10 students pass all their classes?
14. The probability that a certain machine will produce a defective item is 1/4. If a random sample of 6 items is taken from the output of this machine, what is the probability that there will be 5 or more defectives in the sample?
15. T/F
a. We use the t distribution with (n-1) degrees of freedom when sigma, the population standard deviation is stated.