1) what proportion of boys and girls should be selected? 2) How many boys and girls should be selected for a stratified random sample of 30 students? Explain how to obtain this sample question.

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Answer 1 · 2018-08-12T11:49:08

Not sure of part I)

Part ii)

To find a stratified sample it is $\frac{each section}{total} \times \frac{sample size}{1}$ $["each section")/("total")xx("sample size")/1$

Total = boys + girls = 67 + 53 = 120
Sample size is 30

For boys:

$\frac{67}{120} \times \frac{30}{1} = \frac{67}{4} = 16 \frac{3}{4}$ $67/120xx30/1=67/4=16 3/4$ round up to 17 boys

For girls:

$\frac{53}{120} \times \frac{30}{1} = \frac{53}{4} = 13 \frac{1}{4}$ $53/120xx30/1=53/4=13 1/4$ round down to 13 girls