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}=(1.96*12)/(1.9)`
`n=153`

Thus the sample size is 153.

To calculate the range,

Use the confidence interval