The frequency distribution of order lead time at Ecommerce.com from Exercise 18 is repeated below. Lead Time (days) Frequency O up to 5 5 up to 10 7. 10 up to 15 12 15 up to 20 8 20 up to 25 7 Total 40 a. How many orders were filled in less than 10 days? In less than 15 days? b. Convert the frequency distribution to a cumulative frequency distribution. c. Develop a cumulative frequency polygon. d. About 60 percent of the orders were filled in less than how many days?