The article mentioned in Problem 7.48 reported that Treasury bonds had a mean return of -9.3% in 2009. Assume that the returns for the Treasury bonds were distributed as a normal random variable, with a mean of -9.3 and a standard deviation of 10. If you select an individual Treasury bond from this population, what is the probability that it would have a return
a. Less than 0 (i.e., a loss)?
b. Between -10 and -20?
c. Greater than 5?
If you selected a random sample of four Treasury bonds from this population, what is the probability that the sample would have a mean return
d. Less than 0-that is, a loss?
e. Between -10 and -20?
f. Greater than 5?
g. Compare your results in parts (d) through (f) to those in (a) through (c).