Posted by mary on Wednesday, April 13, 2011 at 9:47am.
weekly take home pay for those 20 graduate teaching assistants from university z:
500.75, 217.43, 488.25, 405.78
485.46, 495.48, 370.75, 435.40
479.65, 482.56, 470.28, 489.90
382.50, 500.75, 465.32, 481.25
506.43, 225.50, 504.38, 179.25
1. what are the mean and standard deviation for this distribution of weekly takehome pay amounts?
2. what percentage of the pay amounts lie within 1 standard deviations of the mean?
3. what percentage of the pay amounts lie within 2 standard deviations of the mean?
4. what percentage of the pay amounts lie within 3 standard deviations of the mean?
5. what is the range of the pay amounts?

math  PsyDAG, Wednesday, April 13, 2011 at 10:58am
1. Find the mean first = sum of scores/number of scores
Subtract each of the scores from the mean and square each difference. Find the sum of these squares. Divide that by the number of scores to get variance.
Standard deviation = square root of variance
24. Z score = Score in terms of standard deviations.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions equivalent to the Z scores.
5. Highest value  lowest value = range
I'll let you do the calculations.