578 Assignment 1 F14 Sol

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  1 BA 578 Assignment-Sol- due by Midnight (11:59pm) Monday, Sept 15 th , 2014(Chapters 1, 2, 3 and 4): Total 75 points True/False (One point each) Chapter 1   1. An example of a quantitative variable is the telephone number of an individual. FALSE  2. An example of a interval scale variable is the make of a car. FALSE 3. Credit score is an example of an interval scale variable. TRUE There is no intrinsic Zero. An arbitrary minimum is established. Therefore, it is an interval scale variable.  4. The number of people eating at a local café between noon and 2:00 p.m. is an example of a discrete variable. TRUE Chapter2   5. When establishing the classes for a frequency table it is generally agreed that the more classes you use the better your frequency table will be. FALSE We try to follow the 2 k   rule. Having too many classes is not good.  6. The cumulative distribution function is never decreasing. TRUE It is always increasing and becomes flat at the end point. 7. A Histogram is a graphic that is used to depict quantitative data. TRUE Bar Chart is used for qualitative data. Chapter 3 8. The Mean is the measure of central tendency that divides a population or sample into two equal parts (that is two parts with equal frequencies) FALSE It is the median which does that. 9. If there are 7 classes in a frequency distribution then the fourth class necessarily contains the median. FALSE It depends on the class frequencies  10. The sum of deviations from the mean (taking into account the frequencies) can be negative, zero or positive. FALSE It is always Zero  11. The median is said to be less sensitive to extreme values. TRUE This statement is a relative statement (implicitly) comparing Median with the other popular measure of central tendency, namely, the Mean. But some students read the statement in absolute  2 terms and answered it wrong although they knew that Median is not sensitive to extreme values. Therefore, I removed this question from grading.  12. The Empirical Rule is used to describe a population that is not highly skewed. TRUE It is based on the symmetrical Normal distribution and can be safely applied only for slightly skewed non-Normal distributions. For highly skewed distribution it is not appropriate. Chapter 4   13. If events A and B are independent and A is not an impossible event, then P(A/B) is not equal to zero. TRUE   In fact P(A/B) equals P(A) if A and B are independent, which is not zero unless A is an impossible event. 14. If events A and B are mutually exclusive, then the conditional probability P(A/B) is a  positive number greater than zero but less than 1. FALSE This is obvious from the definition of mutually exclusive events. If B occurs then A cannot occur. Therefore P(A/B) = 0. 15. The union of events A and B is given by all basic outcomes common to both A and B FALSE This statement is for “Intersection” , not for “Union”.   Multiple Choices (each question carries two points): Chapter 1 1. Ratio variables have the following unique or special characteristic: A. Meaningful order B. Predictable C. Categorical in nature D.  An inherently defined zero value 2. Which of the following is a quantitative variable? A. The make of a TV B.  The price of a TV C. The VIN of a car D. The rank of a police officer E. The Driver’s License Number   3. Which of the following is a categorical or Nominal variable? A . The Social Security Number of a person B. Bank Account Balance C. Daily Sales in a Store D. Air Temperature E. Value of Company Stock  3 4. The level of Satisfaction in a Consumer survey would represent a(n) ____________ level of measurement. A. Nominative B.  Ordinal C. Interval D. Ratio Chapter 2 5 . When developing a frequency distribution the class (group), intervals must be A. Large B. Small C.  Mutually exclusive. D. Whole numbers E. Equal Having equal intervals (or nearly equal intervals) is “ generally ” (not always) desirable. But it is not necessary and not even appropriate in some applications. For example, in Income distribution the classes are arbitrarily formed and are generally unequal. Similarly many distributions have the lowest and/or highest class with open bounds which make these class intervals different from other classes.  6. If there are 80 values in a data set, how many classes should be created for a frequency histogram? A. 4 B. 5 C. 6 D . 7 E. 8 Just apply the 2 k   rule for question 8. 7. Consider the following frequency distribution from Excel. What is the missing value? Bin Frequency Cumulative % 584 1 4.00% 1774.4 64.00% 2964.8 4 80.00% 4155.2 3 92.00% 5345.6 1 96.00% More 1 100.00%  4 A.   4 B.   10 C.   12 D.   15 E.   20 Chapter 3 8 . In a statistic class, 10 scores were randomly selected with the following results obtained: 75, 74, 77, 77, 71, 70, 65, 78, 67, and 66. What is the Standard deviation? A. 21.40 B. 23.78 C . 4.88 D. 4.63 E. 214.00 X X    –    (X-bar)   (X-Xbar) 75 3 9 74 2 4 77 5 25 77 5 25 71 -1 1 70 -2 4 65 -7 49 78 6 36 67 -5 25 66 -6 36 720 0 214 s 2x = 214 / (10  –   1) = 23.78 s x  = √2 3.78 = 4.88 9.  According to a survey of the top 10 employers in a major city in the Midwest, a worker spends an average of 413 minutes a day on the job. Suppose the standard deviation is 26.8 minutes and the time spent is approximately a normal distribution. What are the times that approximately 95.45% of all workers will fall?
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