The scores of students on a standardized test are Normally distributed with a mean of 300 and a standard deviation of 40. Between what two values do 99.7% of the test scores lie?
A) 260 to 340
B) 220 to 380
C) 297 to 303
D) 180 to 420

Question

Quizplus · Accepted Answer

According to the empirical rule (68-95-99.7 rule), 99.7% of data in a normal distribution lies within three standard deviations from the mean. Here, the mean is 300 and the standard deviation is 40. So, 300 ± 3(40) gives the range 180 to 420.

The Scores of Students on a Standardized Test Are Normally