Question

Scores on the GRE​ (Graduate Record​ Examination) are normally distributed with a mean of 600 and a standard deviation of 120. Use the 68 dash 95 dash 99.7 Rule to find the percentage of people taking the test who score between 240 and 960.

Answer 1

99.7%

Explanation:

The 68-95-99.7 rule refers to what percentage of data is contained within ranges a certain distance from the mean.

68% of the data lies within one standard deviation of the mean

95% lies within two standard deviations, and

99.7% lies within three standard deviations.

Our mean here is 600, and our standard deviation is 120, so those ranges would be:

480-720 for 1 standard deviation

360-840 for 2 standard deviations, and

240-960 for 3.

Our given range is 240 to 960, three standard deviations from the mean, so the 68-95-99.7 rule tells us that this range contains 99.7% of the people.