To solve this problem using the 68-95-99.7 rule, first we need to find how many standard deviations away from the mean 161 is.
First, we subtract the mean from 161:
161 - 101 = 60
Then, we divide the result by the standard deviation:
60 / 20 = 3
Since 161 is 3 standard deviations away from the mean, we know that the percentage of scores greater than 161 is the same as the percentage of scores more than 3 standard deviations away from the mean. According to the 68-95-99.7 rule, only 0.15% of scores fall more than 3 standard deviations away from the mean.
Therefore, the correct answer is B. 0.15%.
Use the 68-95-99.7 rule to solve the problem
Scores on a test are normally distributed with a mean of 101 and a standard deviation of 20. What percentage of scores are greater than 161?
A. 99.7%
B. 0.15%
C. 99.85%
1 answer