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Statistics: Analyze student exam scores

Students were given an exam with 300 multiple choice questions. The distribution of the scores were normal and the mean was 195 with a standard deviation of 30. you may find it helpful to draw out this distribution before answering the questions below

16. What were the scores of the students who were within one standard deviation of the mean?

17. What percentf the students did that include?

18. What were the scores of students who scored in the middle of the class?

19. If a's are given to students who score 90% or above, what is the minimum z-score of someone getting an a?

20. Let's say you got 235 on this test. Your colleague is in a different section of this course. Her score was 82 out of 100 on her test. in her section the mean was 72 and the standard deviation was 7. Which one of you did better? (hint: compare z-scores)

asked by ro
  1. 16. Z = (score-mean)/SD

    Use Z = +1 and -1.

    17. Mean ± 1 SD = 68.26% (Z Score is your score in terms of SD away from the mean.)

    19. Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.9000) and its Z score.

    20. Take the hint given.

    posted by PsyDAG

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