GCSE Secondary Maths Age 13-17 - Probability & Statistics: Stratified sample - Explained

The video tutorial explains the concept of stratified sampling, which involves creating a sample that is proportional to the entire population. The instructor uses a practical example involving age groups in a village to demonstrate how to calculate the number of people in a stratified sample. The process includes determining the total population, calculating the proportion of each group, and adjusting the sample size to ensure it is representative. The tutorial also covers the importance of using whole numbers in sample calculations and concludes with a discussion on marks allocation for understanding the method.

What is a stratified sample?

• A sample that is randomly selected from a population.

• A sample that includes only the youngest members of a population.

• A sample that includes only the oldest members of a population.

• A sample that is proportional to the entire population.

In the example, how many people over 60 are there in the village?

• 314

• 72

• 50

• 599

How is the number of people over 60 in the sample calculated?

• By dividing the total population by the number of age groups.

• By subtracting the number of people under 21 from the total population.

• By multiplying the proportion of people over 60 by the sample size.

• By adding the number of people under 21 to those over 60.

Why can't the number of people in a stratified sample be a decimal?

• Because it would result in an inaccurate sample size.

• Because it would not be proportional to the population.

• Because people cannot be divided into fractions.

• Because it would be too difficult to calculate.

What is the total number of marks available for the stratified sampling question?

• 3 marks

• 4 marks

• 2 marks

• 1 mark