Question

The population standard deviation for the heights of dogs, in inches, in a city is 3.4 inches. If we want to be 90% confident that the sample mean is within 1 inch of the true population mean, what is the minimum sample size that can be taken?

Answer 1

The minimize size that can be taken is - 31.28 or 31 .

Explanation:

Lets calculate -

Population standard deviation,
`\sigma=3.4 inches`

Margin of error, E = 1

Critical value ,
`z_0_._0_5 =1.645`

Now , the size of the sample ,
`n=((z* \sigma)/(E) )^2`

Putting the given values ,

`=((1.645* 3.4)/(1))^2`

= 31.28 or 31 .

The given table of the question has been attached here .

Hence , the answer is 31.