SAMPLE

Sample

Definition Of Sample

A sample is a part of the population. When a survey is being carried out, a sample is taken from the population one wants to study.

Example of Sample

Conclusions are made about the quality of goods being manufactured in a factory, after inspectors carefully examine a sample of the goods to decide whether the quality is satisfactory.

Video Examples: Stratified Sampling (GCSE Mathematics Handling Data)

Solved Example on Sample

Ques: 3,000 children in a city with a population of 10,000 children watch television for at least 3 hours a day.
How many children in a sample of 100 would watch television for at least 3 hours a day?

Choices:

A. 10
B. 3
C. 30
D.20
Correct Answer: C

Solution:

Step 1: Let x be the number of children in the sample who watch television for at least 3 hours a day.
Step 2:
Step 3:  [Write the proportion.]
Step 4: x × 10000 = 3000 × 100 [Cross multiply.]
Step 5:  [Divide both sides by 10000.]
Step 6:  [Simplify.]
Step 7: So, about 30 children in every 100 would watch television for at least 3 hours a day.

Quick Summary

A sample is a part of a population.
Samples are used to make inferences about the entire population.
The size and method of selection affect the accuracy of the sample.

\[ N_{sample} \subset N_{population} \]

🍎 Teacher Insights

Use real-world examples to illustrate the concept of sampling. Emphasize the importance of randomness in sample selection.

🎓 Prerequisites

Basic arithmetic
Understanding of proportions

Check Your Knowledge

Q1: If a city has 10,000 children and 3,000 watch TV for 3 hours, how many in a sample of 100 would be expected to watch TV for 3 hours?

10 3 30 20

Q2: Which of the following is NOT a characteristic of a good sample?

Representative Random Large Biased

Frequently Asked Questions

Q: Why do we use samples instead of studying the entire population?
A: Studying the entire population can be time-consuming, expensive, or even impossible. Samples provide a practical way to gather information.

Q: How do I choose a good sample?
A: A good sample should be representative of the population and chosen using a random or stratified method to minimize bias.