Question

How many business students must be randomly selected to estimate the mean monthly earnings of business students at one college? We want 95% confidence that the sample mean is within $130 of the population mean, and the population standard deviation is known to be $557.

Answer 1

Number of business students=71

Explanation:

Formula:

Sample Mean= z*(Standard Deviation/
`√(n)`)

where:

n stands for number of business students

z has different values for different Confidence. List is given below:

Confidence z

90% 1.645

92% 1.751

95% 1.96

We will use z=1.96 corresponding to 95% Confidence

130=1.96*(557/
`√(n)`)

n=(1.96*557/130)^2

n=70.52≅71

So number of business students is 71.