How many students must be randomly selected to estimate the mean weekly earnings of students at one college? We want 99% confidence that the sample mean is within $4 of the population mean, and the population standard deviation is known to be $75

Respuesta :

ANSWER:

2333 students

STEP-BY-STEP EXPLANATION:

Given:

Margin of error (E): 4

Standard deviation (σ): 75

Confidence level (CI): 99%

For this confidence level the value of z is equal to 2.576.

We can calculate the necessary sample size with the following formula:

[tex]E=z\cdot\left(\frac{\sigma}{\sqrt{n}}\right)[/tex]

Substituting each value we calculate the value of n, like this:

[tex]\begin{gathered} 4=2.576\cdot \left(\frac{75}{\sqrt{n}}\right) \\ \\ \frac{75}{\sqrt{n}}=\frac{4}{2.576} \\ \\ \sqrt{n}=\frac{75\cdot2.576}{4} \\ \\ n=\left(\frac{75\cdot2.576}{4}\right)^2 \\ \\ n=2332.89\cong2333 \end{gathered}[/tex]

The number of students to be selected must be 2333