## anonymous one year ago The scores of eighth-grade students in a math test are normally distributed with a mean of 57.5 and a standard deviation of 6.5. From this data, we can conclude that 68% of the students received scores between and .

1. anonymous

The standard deviation is a measure of how spread out numbers are. Its symbol is $\sigma$ (the greek letter sigma) The formula is easy: it is the square root of the variance.

2. anonymous

Do you know what a variance is?

3. anonymous

no

4. anonymous

The variance is basically the average of the squared differences from the mean. To calculate the variance follow these steps: Work out the mean (the simple average of the numbers) Then for each number: subtract the mean and square the result (the squared difference). Then work out the average of those squared differences.

5. anonymous

btw, do u have any answer choices?

6. anonymous

ok thank you!