EC315 Quiz Help 2

# EC315 Quiz Help 2 - 1 Which of the following statements...

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1. Which of the following statements regarding the normal distribution is NOT true? A) The mean, median and mode are all equal. B) It has a single peak. C) It is symmetrical. D) The points of the curve meet the X-axis at z = -3 and z = 3. E) All of the above are true. 2. The mean of a normally distributed group of weekly incomes of a large group of executives is \$1,000 and the standard deviation is \$100. What is the z-score for an income of \$1,100? A) 1.00 B) 2.00 C) 1.683 D) -0.90 E) None of the above 3. Ball-Bearings, Inc. produces ball bearings automatically on a Kronar BBX machine. For one of the ball bearings, the mean diameter is set at 20.00 mm (millimeters). The standard deviation of the production over a long period of time was computed to be 0.150 mm. What percentage of the ball bearings will have diameters 20.27 mm or less? (Assume a normal population). A) 41.00% B) 12.62% C) 96.41% D) 85.00% E) 3.59% 4. The average score of 100 students taking a statistics final was 70 with a standard deviation of 7. Assuming a normal distribution, what proportion of the students scored 90 or higher? A) 0.4979 B) 0.0021 C) 0.9979 D) 2.86 E) None of the above 5. What is the area under the normal curve between z = -1.0 and z = -2.0? A) 0.0228 B) 0.3413 C) 0.1359 D) 0.4772 E) None of the above

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6. Past experience of a large manufacturing firm with administering a test to recent college graduates who had applied for a job revealed that the mean test score was 500, and the standard deviation was 50. The distribution of the test scores was normal. Based on this experience, management is considering placing a person whose score is in the upper 6 percent of the distribution directly into a responsible position. What is the lowest score a college graduate must earn to qualify for a responsible position? A) 50
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EC315 Quiz Help 2 - 1 Which of the following statements...

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