Do you know the 68-95-99.7 rule? Approximately 68% of scores in normal distribution are within one standard deviation (34% on each side of the mean), 95% within 2 SD, and 99.7% within 3 SD.
Z = the score in terms of standard deviations = (score-mean)/SD
using the 68- 95-99.7 rule: Assume that a set of test scores is normally distributed with a mean of 100 and a standard diviation of 20. Use the 68-95-99.7 rult to find the following quantities:
percentage of scores less than 100
relative frequency of scores less than 120.
percentage of scores less than 80.
relative frequency of scores less than 60.
Percentage of scores greater than 120.
1 answer
1 answer