# 9.3.1. Collecting Data

A society of 2 150 individuals is divided into 4 social class. A random sample is needed to be selected in which each class is represented by its original size. Complete the missing data in the table.

Classes1234Total
Class Size5003506002 150
Class Sample Size14
• A700, 10, 7, 12, 43
• B700, 36, 25, 43, 804
• C700, 4, 6, 4, 28
• D
2 600
, 5, 7, 4, 30

### Example

A society of 2 150 individuals is divided into 4 social class. A random sample is needed to be selected in which each class is represented by its original size. Complete the missing data in the table.

Classes1234Total
Class Size5003506002 150
Class Sample Size14

### Solution

We know that there is a total of individuals in the society. We have the number of individuals in classes 1, 2, and 4, so the remaining individuals must be in class 3.

There are 700 individuals in class 3, so we can add this information to the table.

Classes1234Total
Class Size500350600
Class Sample Size14

For the sample to represent the society, the ratio of the individuals in each layer of the population must be the same as the ratio of the individuals in each layer of the sample.

Consider the ratio of the class sizes and total society.

Consider the ratio of the class sample size and total sample size.

For the ratios to be equivalent, we get

So, we can now complete the table.

Classes1234Total
Class Size500350600
Class Sample Size14
0
correct
0
incorrect
0
skipped