Question

The population standard deviation for the heights of dogs, in inches, in a city is 7.5 inches. If we want to be 90% confident that the sample mean is within 2 inches of the true population mean, what is the minimum sample size that can be taken

Answer 1

Answer: 39

Explanation:

Formula of sample size :

`n=((z^c*\sigma)/(E))^2` , where
`z^c` = critical z-value for confidence level ,
`\sigma` = population standard deviation , E = margin of error.

`\Rightarrow\ n=((1.645*7.5)/(2))^2\\\\\Rightarrow\ n=(6.16875)^2=38.05347\approx39`

Hence, the minimum sample size that can be taken = 39