Question

the accompanying data represent the approximate population, in millions, of the 20 most populous cities in the world. use these data to construct a frequency distribution with a first class of 7.0 - 7.9. fill in the missing classes and the frequency for each class below.

Explanation:

Step1: List all data values

Data: 13.5, 11.7, 10.2, 8.7, 7.8, 12.9, 11.4, 9.5, 8.1, 7.7, 12.7, 10.5, 9.5, 7.9, 7.6, 12.2, 10.3, 9.2, 7.9, 7.3

Step2: Determine class width

First class: 7.0-7.9, width = 7.9 - 7.0 = 1.0. So classes are consecutive 1.0 intervals.

Step3: Identify missing classes

Classes in order: 7.0-7.9, 8.0-8.9, 9.0-9.9, 10.0-10.9, 11.0-11.9, 12.0-12.9, 13.0-13.9

Step4: Count frequencies for each class

• 7.0-7.9: 7.8,7.7,7.9,7.6,7.9,7.3 → 6 cities
• 8.0-8.9: 8.7,8.1 → 2 cities
• 9.0-9.9:9.5,9.5,9.2 →3 cities

-10.0-10.9:10.2,10.5,10.3 →3 cities
-11.0-11.9:11.7,11.4 →2 cities
-12.0-12.9:12.9,12.7,12.2 →3 cities
-13.0-13.9:13.5 →1 city

(Check total: 6+2+3+3+2+3+1=20, correct)

Answer:

Population (millions of people)	Number of Cities
8.0 – 8.9	2
9.0 – 9.9	3
10.0 – 10.9	3
11.0 – 11.9	2
12.0 – 12.9	3
13.0 – 13.9	1
Total	20