Answer:
n=40 boys
Step-by-step explanation:
-Margin of error is given by the formula:
[tex]E=z\frac{\sigma}{\sqrt{n}}[/tex]
-The z score for a probability of 92% is 1.75
#We make n the subject of the formula and substitute at a 92% confidence:
[tex]E=z\frac{\sigma}{\sqrt{n}}\\\\\sqrt{n}=\frac{z\sigma}{E}\\\\n=[\frac{z\sigma}{E}]^2\\\\\therefore n=[\frac{1.75\times 1.8}{0.5}]^2\\\\=39.69\approx 40[/tex]
Hence, he needs approximately 40 boys for the study
