Ecommerce.com, a large Internet retailer, is studying the lead time (elapsed time between when an order is placed and when it is filled) for a sample of recent orders. The lead times are reported in days.

  Lead Time (days)

Frequency

  0 up to 5

6         

  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 studied?

b.

What is the midpoint of the first class? (Round your answer to 1 decimal place.)

c.

What are the coordinates of the first class for a frequency polygon assuming we draw a frequency polygon using the midpoints? (Round your answer to 1 decimal place.)