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Mathematics 4 ESO – Unit 11 STATISTICS page 119 activity 3

a) Watch the video on “Stratified Sampling” and answer:

I) Using your own words define “stratified sampling”

II) We have a population with 570 students in 3rd and 4th ESO and we want a stratified sample of 60 students.

Girls

Boys

3rd ESO

164

142

4th ESO

126

138

How many students of each category should be in the sample?

  1. b) Watch the video on “Biased Sampling” and answer:
  2. I)  What is the difference between “biased sampling” and “unbiased sampling”?
  3. II)  Which should you use? Why?

     III)  Which survey is the “biased sampling”, the first or the second? why?

  1.   IV)  Which survey is the “unbiased sampling”, the first or the second? why?