Suppose the scores of students on an homework are normally distributed with a mean of 318 and a standard deviation of 40. According to the empirical rule, what percentage of students scored between 238 and 398 on the homework?
Answer: %
Given:
Mean, = 318
Standard deviation, = 40
According to Empirical rule (three sigma rule) 68%, 95% and 99.7% lies within 1, 2 and 3 standard deviations of mean.
So
68% data values lies within One standard deviation of the mean
95% data values lies within Two standard deviation of the mean
99.7% data values lies within Three standard deviation of the mean
Now,
The percentage of students scored between 238 and 398 on the homework :
238 is 2 standard deviations below mean
398 is 2 standard deviations above mean
Using empirical rule, 95% percentage of students scored between 238 and 398 on the homework.
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