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 $12.0. What is the percentage of items that cost: a. Less than $9.0? (Round your answer to 4 decimal places.), b. More than $13.0? (Round your answer to 4 decimal places.), c. Between $10.0 and $12.0? (Round your answer to 4 decimal places.), Find the 60th percentile. Fourty percent of the supermarket items cost more than what amount? (Round your answer to 2 decimal places.)