The average annual amount American households spend for daily transportation is $6312 (Money, August 2001). Assume that the amount spent is normally distributed.
a. Suppose you learn that 5% of American households spend less than $1000 for daily transportation. What is the standard deviation of the amount spent?
b. What is the probability that a household spends between $4000 and $6000?
c. What is the range of spending for the 3% of households with the highest daily transportation cost?