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
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.75 or .25) related to the Z score. Insert the values in the above equation.
I'll let you do the calculations.
98,99,99,103,101,102,104,89,87,90,90
Find the 25th and 75th percentiles.
Within how many standard deviations of the mean is the value 102.
Find the interquartile range.
1 answer
2 answers