Sample questions Quizzes 1-2//MIDTERM AAU MTH 222 MULTIPLE CHOICE 1. Events that have no sample points in common are a. independent events b. posterior events c. mutually exclusive events d. complements ANS: C PTS: 1 TOP: Probability Concepts 2.If A and B are independent events with P(A) = 0.4 and P(B) = 0.6, then P(A B) = a. 0.76 b. 1.00 c. 0.24 d. 0.20 ANS: C PTS: 1 TOP: Probability Concepts 3.If A and B are independent events with P(A) = 0.2 and P(B) = 0.6, then P(A B) = a. 0.62 b. 0.12 c. 0.60 d. 0.68 ANS: D PTS: 1 TOP: Probability Concepts 4.If A and B are independent events with P(A) = 0.05 and P(B) = 0.65, then P(A B) = a. 0.05 b. 0.0325 c. 0.65 d. 0.8 ANS: A PTS: 1 TOP: Probability Concepts 5.A survey of a sample of business students resulted in the following information regarding the genders of the individuals and their selected major. Selected Major Gender Management Marketing Others Total Male 40 10 30 80 Female 30 20 70 120 Total 70 30 100 200 a. What is the probability of selecting an individual who is majoring in Marketing? b. What is the probability of selecting an individual who is majoring in Management, given that the person is female? c. Given that a person is male, what is the probability that he is majoring in Management? d. What is the probability of selecting a male individual?
ANS: a. 0.15 b. 0.25 c. 0.50 d. 0.40 PTS: 1 TOP: Probability Concepts 6.The collection of all possible sample points in an experiment is a. the sample space b. a sample point c. an experiment d. the population ANS: A PTS: 1 TOP: Probability Concepts 7.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 ANS: B PTS: 1 TOP: Discrete Probability Distributions 8.The number of electrical outages in a city varies from day to day. Assume that the number of electrical outages (x) in the city has the following probability distribution. x f(x) 0 0.80 1 0.15 2 0.04 3 0.01 The mean and the standard deviation for the number of electrical outages (respectively) are a. 2.6 and 5.77 b. 0.26 and 0.577 c. 3 and 0.01 d. 0 and 0.8 ANS: B PTS: 1 TOP: Discrete Probability Distributions NARRBEGIN: Exhibit 05-01 Exhibit 5-1 The following represents the probability distribution for the daily demand of computers at a local store. Demand Probability 0 0.1 1 0.2
NARREND 2 0.3 3 0.2 4 0.2 9. Refer to Exhibit 5-1. The expected daily demand is a. 1.0 b. 2.2 c. 2, since it has the highest probability d. of course 4, since it is the largest demand level ANS: B PTS: 1 TOP: Discrete Probability Distributions NAR: Exhibit 05-01 10. Refer to Exhibit 5-1. The probability of having a demand for at least two computers is a. 0.7 b. 0.3 c. 0.4 d. 1.0 ANS: A PTS: 1 TOP: Discrete Probability Distributions 11. The center of a normal curve is a. always equal to zero b. is the mean of the distribution c. cannot be negative d. is the standard deviation ANS: B PTS: 1 TOP: Continuous Probability Distributions 12. The probability that a continuous random variable takes any specific value a. is equal to zero b. is at least 0.5 c. depends on the probability density function d. is very close to 1.0 ANS: A PTS: 1 TOP: Continuous Probability Distributions 13. A normal distribution with a mean of 0 and a standard deviation of 1 is called a. a probability density function b. an ordinary normal curve c. a standard normal distribution d. none of these alternatives is correct ANS: C PTS: 1 TOP: Continuous Probability Distributions 14. The z score for the standard normal distribution a. is always equal to zero b. can never be negative c. can be either negative or positive d. is always equal to the mean
ANS: C PTS: 1 TOP: Continuous Probability Distributions 15. A uniform probability distribution is a continuous probability distribution where the probability that the random variable assumes a value in any interval of equal length is a. different for each interval b. the same for each interval c. at least one d. None of these alternatives is correct. ANS: B PTS: 1 TOP: Continuous Probability Distributions 16. Consider a binomial probability experiment with n = 3 and p = 0.1. Then, the probability of x = 0 is a. 0.0000 b. 0.0001 c. 0.001 d. 0.729 ANS: D PTS: 1 TOP: Continuous Probability Distributions 17. Z is a standard normal random variable. The P (1.20 Z 1.85) equals a. 0.4678 b. 0.3849 c. 0.8527 d. 0.0829 ANS: D PTS: 1 TOP: Continuous Probability Distributions 18. Given that Z is a standard normal random variable, what is the probability that -2.51 Z -1.53? a. 0.4950 b. 0.4370 c. 0.0570 d. 0.9310 ANS: C PTS: 1 TOP: Continuous Probability Distributions 19. 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 ANS: A PTS: 1 TOP: Continuous Probability Distributions 20. 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 ANS: B PTS: 1 TOP: Continuous Probability Distributions
21. Approximate the following binomial probabilities by the use of normal approximation. a. P(X = 18, n = 50, p = 0.3) b. P(X 15, n = 50, p = 0.3) c. P(X 12, n = 50, p = 0.3) d. P(12 X 18, n = 50, p = 0.3) ANS: a. 0.0805 b. 0.5596 c. 0.2206 d. 0.7198 PTS: 1 TOP: Continuous Probability Distributions 22.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 ANS: B PTS: 1 TOP: Sampling 23.A simple random sample of 100 observations was taken from a large population. The sample mean and the standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is a. 1.20 b. 0.12 c. 8.00 d. 0.80 ANS: A PTS: 1 TOP: Inference 24. The sample statistic s is the point estimator of a. μ b. σ c. d. ANS: B PTS: 1 TOP: Inference 25. The sample mean is the point estimator of a. μ b. σ c. d. ANS: A PTS: 1 TOP: Inference 26. As the sample size becomes larger, the sampling distribution of the sample mean approaches a a. binomial distribution b. Poisson distribution
c. normal distribution d. chi-square distribution ANS: C PTS: 1 TOP: Sampling 27. A simple random sample of 64 observations was taken from a large population. The sample mean and the standard deviation were determined to be 320 and 120 respectively. The standard error of the mean is a. 1.875 b. 40 c. 5 d. 15 ANS: D PTS: 1 TOP: Sampling