From a population with a variance of 900, a sample of 225 items is selected. At 95% confidence, the margin of error is
A)15
B)2
C)3.92
D)4

Question

Quizplus · Accepted Answer

We can use the formula for the margin of error:
Margin of error = Z * (standard deviation / square root of sample size)
At 95% confidence, the Z-value is 1.96.
The standard deviation is the square root of the variance, which is 30.
The square root of the sample size is the square root of 225, which is 15.
Putting all of this together, we get:
Margin of error = 1.96 * (30 / 15) = 3.92
Therefore, the best choice is C, with a margin of error of 3.92.

From a Population with a Variance of 900, a Sample