Help The cost per item at a supermarket follows an exponential distribution. There are many inexpensive items and a few relatively expensive ones. The mean cost per item is $4.5. What is the percentage of items that cost: a. Less than $1.5? (Round your answer to 4 decimal places.) Probability b. More than $5.5? (Round your answer to 4 decimal places.) Probability c. Between $2.5 and $4.5? (Round your answer to 4 decimal places.) Probability d. Find the 20th percentile. Eighty percent of the supermarket items cost more than what amount? (Round your answer to 2 decimal places.)