Question 1133774: The graph illustrates the distribution of test scores taken by College Algebra students. The maximum possible score on the test was 130, while the mean score was 70 and the standard deviation was 14.
(Below shows numbers on the x axis with a bell curve. 28 and 112 are on the edges of the bell curve, while 42 through 98 are within the curve. 70 is exactly in the middle).
___28______42_____56____70______84_______98________112____
Distribution of test scores
(a) What is the approximate percentage of students who scored lower than 28 on the test?__________%
(b) What is the approximate percentage students who scored between 56 and 84 on the test?________ %
(c) What is the approximate percentage of students who scored between 70 and 84 on the test?_________ %
(d) What is the approximate percentage of students who scored higher than 98 on the test?__________ %
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! difference from mean/14 is z-score
z<=-3 for a score of 28 (28-70)/14. This would be about 0.0013 or 0.13%
z<=-2 for a score of 42, and that is about 0.0228
z<=-1 for a score of 56 and +1 for a score of 84. That is about 68%
between 70 and 84 is a z-score between 0 and 1, and that is about 34%
Higher than 98 is greater than 2 standard deviations, and that is 2.28%
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