U.S. consumers are increasingly viewing debit cards as a convenient substitute for cash and checks. The average amount spent annually on a debit card is $7,790 (Kiplinger's , August 2007). Assume that the average amount spent on a debit card is normally distributed with a standard deviation of $500.
a. A consumer advocate comments that the majority of consumers spend over $8,000 on a debit card. Find a law in this statement.
b. Compute the 25th percentile of the amount spent on a debit card.
c. Compute the 75th percentile of the amount spent on a debit card.
d. What is the interquartile range of this distribution?