The following data represent the number of live multiple-delivery births (three or more babies) in 2007 for women 15 to 54 years old.

Age ....Number of Multiple Births

15–19 ..... 100

20–24 ..... 467

25–29 .....1620

30–34 .....2262

35–39 .....1545

40–44 ..... 328

45–54 ..... 105

(a) Construct a probability model for number of multiple births.

(b) In the sample space of all multiple births, are multiple births for 15- to 19-year-old mothers unusual?

(c) In the sample space of all multiple births, are multiple births for 40- to 44-year-old mothers unusual?