Question

Assume that a normal distribution of data has a mean of 22 and a standard deviation of 3. Use the 68minus 95minus99.7 rule to find the percentage of values that lie below 25 .

Answer 1

Given that, mean = 22 and

standard deviation = 3

According to 69-95-99.7 rule, approximately 68% of the data fall within 1 standard deviations of the mean.

Therefore, 100 - 68 = 32% of the data fall outside the 1 standard deviations of the mean. That means 32/2 = 16% of the data fall either side of the 1 standard deviations of the mean.

Hence, 16 + 68 = 84% of values that lie below 25.

Answer: 84%