Suppose the scores of students on an exam are normally distributed with a mean of 520 and a standard deviation of 91. Then approximately 68% of the exam scores lie between the intergers____ and ____ such that the mean is halfway between these two intergers.
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Suppose the scores of students on an exam are
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- A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1537 and the standard deviation was 315. The test scores of four students selected at random are 1930, 1270, 2280, and 1420. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The Z-score for 1930 is. (Round two decimal places as needed.).Tim is a researcher who is dealing with a SAMPLE of scores. The SAMPLE of scores is: 15, 17, 19, 22, 10, 23, 16, 15. Tim calculates the Sum of Squares for this SAMPLE of scores and finds that S.S. = 122.88. For this SAMPLE, find both the variance and standard deviation.A math teacher gives two different tests to measure students' aptitude for math. Scores on the first test are normally distributed with a mean of 23 and a standard deviation of 4.2. Scores on the second test are normally distributed with a mean of 71 and a standard deviation of 10.8. Assume that the two tests use different scales to measure the same aptitude. If a student scores 29 on the first test, what would be his equivalent score on the second test? (That is, find the score that would put him in the same percentile.)
- Suppose a waitress keeps track of her tips, as a percentage of the bill, for a random sample of 60 tables. Suppose that, unknown to the waitress, her population mean tip percentage is 14%, with a standard deviation of 3%. Between what two values is there a 68% chance that her sample mean tip percentage will fall?A set of final examination grades in an introductory statistics course is normally distributed, with a mean of 78 and a standard deviation of 7. If the professor grades on a curve (for example, the professor could give A's to the top 10% of the class, regardless of the score), is a student better off with a grade of 92 on the exam with a mean of 78 and a standard deviation of 7 or a grade of 64 on a different exam, where the mean is 61 and the standard deviation is 3? Show your answer statistically and explain.A standardized exam's scores are normally distributed. In a recent year, the mean test score was 1464 and the standard deviation was 310. The test scores of four students selected at random are 1880, 1200, 2170, and 1360. Find the z-scores that correspond to each value and determine whether any of the values are unusual. The z-score for 1880 is (Round to two decimal places as needed.) The z-score for 1200 is (Round to two decimal places as needed.) The z-score for 2170 is (Round to two decimal places as needed.) The z-score for 1360 is. (Round to two decimal places as needed.) Which values, if any, are unusual? Select the correct choice below and, if necessary, fill in the answer box within your choice. O A. The unusual value(s) is/are (Use a comma to separate answers as needed.) O B. None of the values are unusual.
- Suppose there are 5 students in a room. The mean age is 20.0 years, and the median age is 19. If the youngest person leaves and is not replaced by another person, what happens to the mean and the median? The mean either increases or stays the same, and the median increases. The median either increases or stays the same, and the mean increases. The mean increases, but it is impossible to determine whether the median increases, decreases, or stays the same.Assume that an intelligence test scores are distributed normallt with a mean of 100 and a standard deviation of 15. If you scored 124 on this intelligence test, what is your z-score on this distribution.Test scores for a Statistics class have a mean of 81 with a standard deviation of 4. Test scores for a calculus class had a mean of 75 with a standard deviation of 3.5. Suppose a student gets an 87 on the statistics test andan 86 on the calculus test. Calculate the z-scores for each test. On which test did the student perform better relative to the other students in the class.
- Suppose that, at the end of last semester, Marie gave her introductory statistics class a final exam. After grading these exams, she created a histogram illustrating the distribution of exam scores for the 70 students in the class. Each of the bars in this histogram includes only the left endpoint of the interval, except for the bar representing scores between 90 and 100 points, which also includes the right endpoint. What percentage of students scored between 60 and 80 points on the exam? Round your answer to the nearest tenth of a percent. Number of students who scored at least 80 points = students Percentage of students who scored between 60 and 80 points = %Suppose the scores on a college entrance examination are normally distributed with a mean of 525 and a standard deviation of 110. A certain prestigious university will consider admission only for those applicants whose scores exceed the 95th percentile of the distribution. Find the minimum score an applicant must achieve in order to receive consideration for admission to the university. Round your answer up to the nearest integer.The amounts of electricity bills for all households in a particular city have an approximately normal distribution with a mean of $135 and a standard deviation of $25. Let I be the mean amount of electricity bills for a random sample of 24 households selected from this city. Find the mean and standard deviation of
