Lesson 8 - Shapes

Question 3 suppose the professor decides to give a c

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Unformatted text preview: give a C to the 2/3 of the students who score in the middle. Between what two scores (approximately) would a student have to get to earn a C on the exam? Answer 1: 16% (as 90 is one standard deviation greater than the mean) Answer 2: Since 60 is 2 standard deviations less than the mean, approximately 2.5% of students would score less than 60. 2.5% of 300 is 7.5. So, about 7 or 8 students would fail the exam. Answer 3: 2/3 is approximately 68%. From the rule, about 68% of the data fall within one standard deviation of the mean. So, approximately 2/3 of the students would score between 70 and 90. Example 8.5 Suppose scores on exam 1 are normally distributed with a mean of 80 and a standard deviation of 10. Suppose scores on exam 2 are normally distributed with a mean of 75 and a standard deviation of 5. Question: Rachel scored an 85 on the first exam and an 80 on the second exam. On which exam was her performance better compared to the rest of the class? Answer: Exam 1: Rachel’s score of 85 is 0.5 standar...
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