Stat 351

13. X is a normally distributed random variable with a mean of 12 and a standard deviation of 3. The probability that X equals 19.62 is a. 0.000 b. 0.0055 c. 0.4945 d. 0.9945

a

21. The uniform probability distribution is used with a. A continuous random variable b. A discrete random variable c. A normally distributed random variable d. Any random variable, as long as it is not nominal

a

3. In a standard normal distribution, the range of values of z is from a. minus infinity to infinity b. -1 to 1 c. 0 to 1 d. -3.09 to 3.09

a

6. The mean of a standard normal probability distribution a. Is always equal to zero b. Can be any value as long as it is positive c. Can be any value d. Is always greater than zero

a

8. A normal probability distribution a. Is a continuous probability distribution b. Is a discrete probability distribution c. Can be either continuous or discrete d. Must have a standard Deviation of 1

a

9. An experiment consists of making 80 telephone calls in order to sell a particular insurance policy. The random variable in this experiment is a a. Discrete random variable b. Continuous random variable c. Complex random variable d. Simplex random variable

a

9. The sample mean is the point estimator of a. μ b. σ c. x̄ d. p-bar

a

10. An experiment consists of determining the speed of automobiles on a highway by the use of radar equipment. The random variable in this experiment is a a. Discrete random variable b. Continuous random variable c. Complex random variable d. Simplex random variable

b

11. The number of customers that enter a store during one day is an example of a. A continuous random variable b. A discrete random variable c. Either a continuous or a discrete random variable, depending on the number of the customers d. Either a continuous or a discrete random variable, depending on the gender of the customers

b

13. The Poisson probability distribution is a a. Continuous probability distribution b. Discrete probability distribution c. Uniform probability distribution d. Normal probability distribution

b

3. A probability distribution showing the probability of x successes in n trial, is termed a a. Uniform probability distribution b. Binomial probability distribution c. Hypergeometric probability distribution d. Normal probability distribution

b

3. The process of analyzing sample data in order to draw conclusions about the characteristics of a population is called a. Descriptive Statistics b. Statistical inference c. Data analysis d. Data summarization

b

4. Parameters are a. Numerical characteristics of a sample b. Numerical characteristics of a population c. The averages taken from a sample d. Numerical characteristics of either a sample or a population

b

4. Variance is a. A measure of the average, or central value of a random variable b. A measure of the dispersion of a random variable c. The square root of the standard deviation d. The sum of the squared deviation of data elements from the mean

b

7. The standard deviation of a standard normal distribution a. Is always equal to zero b. Is always equal to one c. Can be any positive value d. Can be any value

b

8. In point estimation a. Data from the population is used to estimate the population parameter b. Data from the sample is used to estimate the population parameter c. Data from the sample is used to estimate the sample statistic d. The mean of the population equals the mean of the sample

b

10. Whenever the population has a normal probability distribution for a. Only large sample sizes b. Only small sample sizes c. Any sample size d. Only samples of size thirty or greater

c

11. a. The expected value of the sample statistic is equal to zero b. The expected value of the sample statistic is equal to one c. the expected value of the sample statistic is equal to the population parameter d. it is equal to zero

c

14. The expected value of a discrete random variable a. Is the most likely or highest probability value for the random variable b. Will always be one of the values x can take on, although it may not be the highest probability value for the random variable c. Is the average value for the random variable over many repeats of the experiment d. None of these alternatives is correct

c

15. Which of the following is not a characteristic of an experiment where the binomial probability distribution is applicable? a. The experiment has a sequence of n identical trials b. Exactly two outcomes are possible on each trial c. The trials are dependent d. The probabilities of the outcomes do not change from one trial to another.

c

16. A sample of 25 observations is taken from an infinite population. The sampling distribution of P-bar is a. Not normal since n<30 b. Approximately normal because P-bar is always normally distributed c. Approximately normal if np≥5 and n(1-P)≥5 d. Approximately normal if np>30 and n(1-P) >30

c

16. Which of the following is a characteristic of a binomial experiment? a. At least 2 outcomes are possible b. The probability changes from trial to trial c. The trials are independent d. The probabilities of the outcomes do not change from one trial to another

c

20. The expected value for a binomial probability distribution is a. E(x)= Pn(1-n) b. E(x)= P(1-P) c. E(x)= nP d. E(x)= nP(1-P)

c

4. Which of the following is not a characteristic of the normal probability of distribution? a. Symmetry b. The total area under the curve is always equal to 1 c. 99.72% of the time the random variable assumes a value within plus or minus 1 standard deviation of its mean d. The mean is equal to the median, which is also equal to the mode.

c

8. A measure of the average value of a random variable is called a(n) a. Variance b. Standard deviation c. Expected value d. Coefficient of Variation

c

1. A numerical description of the outcome of an experiment is called a a. Descriptive statistic b. Probability function c. Variance d. Random variable

d

12. If you are conducting an experiment where the probability of a success is 0.02 and you are interested in the probability of 4 successes in 15 trials, the correct, the correct probability function to use is the a. Standard normal probability density function b. Normal probability density function c. Poisson probability function d. Binomial probability function

d

14. For a population with any distribution, the form of the sampling distribution of the sample mean is a. Sometimes normal for all sample sizes b. Sometimes normal for large sample sizes c. Always normal for all sample sizes d. Always normal for large sample sizes

d

19. The standard deviation of a binomial distribution is a. E(x)= P(1-P) b. E(x)= nP c. E(x)= nP(1-P) d. None of these alternatives is correct

d

2. Which of the following is not a characteristic of the normal probability distribution? a. The mean, median, and mode are equal. b. The mean of the distribution can be negative, zero, or positive. c. The distribution is symmetrical d. The standard deviation must be 1

d

6. The closer the sample mean is to the population mean, a. The larger the sampling error b. The smaller the sampling error c. The sampling error equals 1 d. None of these alternatives is correct

d

7. Which of the following is a required condition for a discrete probability function? a. Sum of P(x)= 0 b. P(x)≥ 1 for all values of x c. P(x)<0 d. Sum of P(x)=1

d

9. If the mean of a normal distribution is negative, a. The standard deviation must also be negative b. The variance must also be negative c. A mistake has been made in the computations, because the mean of a normal distribution can not be negative d. None of these alternatives is correct.

d