Question

Based upon extensive data from a national high school educational testing​ program, the standard deviation of national test scores for mathematics was found to be 121 points. If a sample of 256 students are given the​ test, what would be the standard error of the​ mean?

Answer 1

The standard error of the mean is 7.56

Explanation:

The standard error of the mean is defined as the ratio of standard deviation to the square root of the sample size of a data. The standard error of the mean is mathematically expressed as shown below;

`X = (\sigma)/(√(n) )`

X is the standard error of the mean

`\sigma` is the standard deviation

n is the sample size.

Given;

`\sigma = 121\\n = 256`

On substitution into the formula we have;

`X = (121)/(√(256) )`

`X = (121)/(16) }\\`

X ≈ 7.56