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*There are 400 students in the senior class at Oak Creek High School. The number of students who scored within 2 standard deviations of the mean is approximately*

*There are 400 students in the senior class at Oak Creek High School. The number of students who scored within 2 standard deviations of the mean is approximately*

August 7, 2019

2019 Algebra II Regent Exam

Question 18

There are 400 students in the senior class at Oak Creek High School. All of these students took the SAT. The distribution of their SAT scores is approximately normal. The number of students who scored within 2 standard deviations of the mean is approximately

(1) 75

(2) 95

(3) 300

(4) 380

Answer and Explanation:

Standard deviation is a term that is used to tell how far from the mean (average) the scores lie. Whenever distribution and standard deviation is mentioned on the Regent Exam, students need to refer to their memory of the normal distribution curve. The mean is in the middle. One standard deviation in both directions, up and down, is 68% of the whole population. Two standard deviations in both directions is 95% of the population. Since the problem referred to students who scored within 2 standard deviations, all we need to do is take 95% of 400.

400*.95 = 380. Therefore, choice 4 is the correct answer choice.

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