STA QUIZ

Mid Term Exam 1. The set of measurements collected for a particular element is (are) called

a. census b. variables c. observations d. samples

2. A characteristic of interest for the elements is called a(n) a. sample b. data set c. variable d. observation

3. All the data collected in a particular study are referred to as the a. census b. inference c. variable d. data set

4. In a data set, the number of observations will always be the same as the number of

a. variables b. elements c. data sets d. data

5. Which of the following is NOT a scale of measurement? a. nominal b. ordinal c. interval d. All of these are scales of measurement.

6. In constructing a frequency distribution, as the number of classes are decreased, the class width a. decreases b. remains unchanged c. increases d. can increase or decrease depending on the data values

7. If several frequency distributions are constructed from the same data set, the distribution with the widest class width will have the a. fewest classes b. most classes c. same number of classes as the other distributions since all are constructed from the same

data d. None of the other answers are correct.

8. Excel's __________ can be used to construct a frequency distribution for categorical data. a. DISTRIBUTION function b. SUM function c. FREQUENCY function d. COUNTIF function

9. A tabular summary of a set of data showing the fraction of the total number of items in several nonoverlapping classes is a a. frequency distribution. b. relative frequency distribution. c. frequency. d. cumulative frequency distribution.

10. The relative frequency of a class is computed by a. dividing the midpoint of the class by the sample size. b. dividing the frequency of the class by the midpoint. c. dividing the sample size by the frequency of the class. d. dividing the frequency of the class by the sample size.

11. The interquartile range is the difference between the

a. first and second quartiles b. first and third quartiles c. second and third quartiles d. second and fourth quartiles

12. The coefficient of determination is equal to the a. absolute value of the correlation coefficient b. squared value of the correlation coefficient c. square-root of the correlation coefficient d. inverse value of the correlation coefficient

13. Generally, which one of the following is the least appropriate measure of central tendency for a data set that contains outliers? a. mean b. median c. 2nd d.

quartile 50th

percentile

14. An important measure of location for categorical data is the a. mean b. median c. mode d. margin

15. The measure of variability easiest to compute, but seldom used as the only measure, is the a. range b. interquartile range c. standard deviation d. variance

16. The sample space refers to a. any particular experimental outcome b. the sample size minus one c. the set of all possible experimental outcomes d. both any particular experimental outcome and the set of all possible experimental

outcomes are correct

17. An experiment consists of three steps. There are four possible results on the first step, three possible results on the second step, and two possible results on the third step. The total number of experimental outcomes is a. 9 b. 14 c. 24 d. 36

18. An experiment consists of tossing 4 coins successively. The number of sample points in this experiment is a. 16 b. 8 c. 4 d. 2

19. A lottery is conducted using three urns. Each urn contains chips numbered from 0 to 9. One chip is selected at random from each urn. The total number of sample points in the sample space is a. 30 b. 100 c. 729 d. 1,000

20. Three applications for admission to a local university are checked to determine whether each applicant is male or female. The number of sample points in this experiment is a. 2 b. 4 c. 6 d. 8

21. Which of the following is not a.

a required condition for a discrete probability function? f(x) ≥ 0 for all values of x

b. ∑f(x) = 1 c. ∑f(x) = 0 d. All of the answers are correct.

22. Which of the following statements about a discrete random variable and its probability distribution are

true? a. Values of the random variable can never be negative. b. Negative values of f(x) are allowed as long as ∑ f(x) = 1. c. Values of f (x) must be greater than or equal to zero. d. The values of f (x) increase to a maximum point and then decrease.

23. A measure of the average value of a random variable is called a(n) a. variance b. standard deviation c. expected value d. None of the answers is correct.

24. A weighted average of the value of a random variable, where the probability function provides weights is known as a. a probability function b. a random variable c. the expected value d. None of the answers is correct

25. The expected value of a random variable is the a. value of the random variable that should be observed on the next repeat of the experiment b. value of the random variable that occurs most frequently c. square root of the variance d. None of the answers is correct.

26. The random variable x is known to be uniformly distributed between 70 and 90. The probability of x having a value between 80 to 95 is a. 0.75 b. 0.5 c. 0.05 d. 1

27. The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability density function has what value in the interval between 6 and 10? a. 0.25 b. 4.00 c. 5.00 d. zero

28. The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability of assembling the product between 7 to 9 minutes is a. zero b. 0.50 c. 0.20 d. 1

29. The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability of assembling the product in less than 6 minutes is a. zero b. 0.50 c. 0.15 d. 1

30. The assembly time for a product is uniformly distributed between 6 to 10 minutes. The probability of assembling the product in 7 minutes or more is a. 0.25 b. 0.75 c. zero d. 1