1a. 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
Range = highest score - lowest
1b. Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score. Make your decision from that.
I'll let you do the calculations.
1. A simple random sample of FICO credit rating scores is listed below:
714 751 664 789 818 779 698 836 753 834 693 802
a. Find range, variance, and standard deviation.
b. As of this writing, the mean FICO score was reported to be 678. Based on these results, is a FICO score of 500 unusual? Why or why not?
1 answer
2 answers