2.55 The breakdown of U.S. cities having a population of at least 10,000 persons has been reported as follows.

Population Number of Cities 10,000–under 25,000 1510 25,000–under 50,000 684 50,000–under 100,000 430 100,000–under 250,000 191 250,000–under 500,000 37 500,000–under 1,000,000 25 1,000,000 or more 9

a. How many cities have a population of at least 25,000 but less than 500,000?

b. How many cities have a population less than 250,000?

c. How many cities have a population of at least 100,000 but less than 1,000,000? What percentage of cities are in this group?

d. What is the class mark for the 100,000–under 250,000 class?

e. Convert the table to a relative frequency distribution.