Question

The Mean on a statewide geography test was 74 with a standard Deviation of 12. west country sampled the scores of some of its students and reported a mean of 79 with a margin of error of + or - 1.9. to the nearest whole number how many students were in west county's sample?

Answer 1

For population, the mean is 74 and standard deviaton is 12.

For sample, the mean is 79 and margin error are

$\pm\text{ 1.9.}$

Let alpha is 0.05 for which z score is 1.96.

Apply the margin of error formula,

$M=\pm z\frac{\sigma}{\sqrt[]{n}}$

Substitute the value.

$\sqrt[\square]{n}=\frac{1.96\times12}{1.9}$$n=153$

Thus the sample size is 153.

To calculate the range,

Use the confidence interval

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