6. If the variance of grades in an Economics course is 25, each student should unconditionallyexpect their grade to deviate from the class average grade by...50 points20 points10 points5 pointsUntitled Notepad

Given that: The variance of grades in an Economics course is 25.

Answered: 6. If the variance of grades in an…

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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1. 2. 4. 1. 2. The distribution of a sample of 100 test scores is mound-shaped and symmetrical, with a mean of 50 and a variance of 144. 3. a) b) c) 4. d) 3. a) a) A sample of 200 people were given a test. The distribution of the test scores was mound- shaped and symmetrical with a mean of 100. One person, whose test score was 125, was found to be at the 84th percentile. b) d) Answers: b) Approximately how many scores are equal to or greater than 74? What score corresponds to the 75th percentile? If the lowest and highest scores in this sample are 14 and 89, respectively, what is the range of the scores in standard deviation units? b) Assume that the 100 test scores still have a mean of 50 and a variance of 144, but now have a strongly negatively skewed distribution. At least how many of the scores fall between 32 and 68 in this distribution? What is the Z-score of a person whose test score is 70? Approximately how many people obtained scores greater than 135? Approximately how many…
5. For each of the following, state whether the statement is true or false and justify your answer. a) If a distribution is skewed, it's better to give the median and IQR instead of the mean and standard deviation. b) A man is in the 96th percentile for blood pressure in his age group. This means his blood pressure is better than 96% of those in his age group. c) Two variables X and Y have a correlation of 0. This means the two have no relationship. d) For a continuous random variable X, P(X < x) = P(X < x). e) The main benefit of an observational study is we can determine causation between two variables. f) Let X be the time until a car arrives at a stop sign. Then we can model X as X * Ga(r,2) for some r and 1.
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 = %
We are interested in determining whether or not the variances of the sales at two music stores (A and B) are equal. A sample of 16 days of sales at store A has a sample variance of 20 while a sample of 26 days of sales from store B has a sample variance of 30. The test statistic is
Here is an example from John and Jenn. When we return exams in our classes, we find it beneficial to share with students information on the distribution of scores. We provide this information so that students will have an idea of how they scored on the exam in comparison to their peers. However, deciding which descriptive information to provide to the class is not always an easy decision. These are modified grades from one of Jenn’s statistics classes. For this data set, the mean is 77, the mode is 92, and the median is 86. If you were the professor of the class, do you think sharing the mean scores on the exam with the class is a representative score of the data set? Why or why not? 9 or 11. The researchers predicted that the more a mother weighed during pregnancy, the higher the fat mass would be in the child. Such findings would support the developmental over nutrition hypothesis, which states that overeating during key developmental times has an influence on the offspring. The…
Express the alternative hypothesis in symbolic form. A psychologist claims that the mean amount of time (in hours) that females spend in talk therapy is more than that of men. Assume that two samples are independent. Let the female talk therapy times be the first population and the male talk therapy times be the second population.
On average, a sample of n = 36 scores will provide a better estimate of the population mean than a sample of n = 49 scores from the same population.
It is possible to have a variance of 625,000625,000 for some data set. true or false

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6. If the variance of grades in an Economics course is 25, each student should unconditionally expect their grade to deviate from the class average grade by... 50 points 20 points 10 points 5 points