Test 2 B58
Test 2 - Bus XXXXXXXXXXName _____________________________
A.M. Ward Chapters 5-8
1. If two events A and B are mutually exclusive, what does the special rule of addition state?
A. P(A or B) = P(A) + P(B) B. P(A and B) = P(A) + P(B)
C. P(A and/or B) = P(A) + P(B) D. P(A or B) = P(A) – P(B)
2. Which approach to probability is exemplified by the following formula?
Probability of an Event =
Number of times an event occurred in the past
Total number of observations
A. Classical approach B. Empirical approach C. Subjective approach D. None of the above
3. A lamp manufacturer has developed five lamp bases and three lampshades that could be used together. How
many different arrangements of base and shade can be offered?
A. 5 B. 10 C. 15 D. 20
4. The first card selected from a standard 52-card deck was a king. If it is returned to the deck, what is the
probability that a king will be drawn on the second selection?
A. 1/4 or XXXXXXXXXXB. 1/13, or 0.077 C. 12/13, or 0.923 D. 1/3 or 0.33
5. An experiment may have (after the experiment is done):
A. Only one result B. Only two results C. Two or more results D. None of the above
6. When are two events mutually exclusive?
A. They overlap on a Venn diagram B. If one event occurs, then the other cannot
C. Probability of one affects the probability of the other D. Both (a) and (b)
7. The result of a particular experiment is called a(n)
A. observation. B. conditional probability. C. event. D. outcome.
8. The probability of two or more events occurring concurrently is called a(an)
A. conditional probability. B. empirical probability. C. joint probability. D. tree diagram.
E. none of the above.
9. A graphical method useful in calculating joint and conditional probability is
A. a tree diagram. B. a Venn diagram. C. a histogram. D. inferential statistics.
10. When applying the special rule of addition for mutually exclusive events, the joint probability is:
A. 1 B. .5 C. 0 D. unknown
11. If the variance of a probability was computed to be 36 grams, what is the standard deviation?
A. 0.6 B. 1.9 C. 6.0 D. 12.96
12. Sixty percent of the customers of a fastfood chain order the Whopper, french fries and a drink. If a random
sample of 15 cash register receipts is selected, what is the probability that 10 or more will show that the above
three food items were ordered?
A. 1,000 B XXXXXXXXXXC XXXXXXXXXXD. 0.000
13. The probabilities and the number of automobiles lined up at a Lakeside Olds at opening time (7:30 a.m.) for
On a typical day, how many automobiles should Lakeside Olds expect to be lined up at opening?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. 1.96
14. An insurance agent has appointments with four prospective clients tomorrow. From past experience the
agent knows that the probability of making a sale on any appointment is 1 out of 5. Using the rules of
probability, what is the likelihood that the agent will sell a policy to 2 of the 4 prospective clients?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. 0.026
15. In which of the following discrete distribution does the probability of a success NOT vary from one trial to
A. Binomial B. Uniform C. Hypergeometric D. All of the above
16. Which of the following is a requirement for use of the hypergeometric distribution?
A. Only 2 possible outcomes B. Trials are independent
C. Probability of a success is greater than 1.0 D. All of the above
17. Which is true for a binomial distribution?
A. There are three or more possible outcomes B. Probability of success remains the same from trial to trial
C. Value of p is equal to XXXXXXXXXXD. All of the above are correct
18. The weight of an offensive linesman may be 205 pounds, 210 pounds, 225 pounds or 219 pounds. What is
this an illustration of?
A. Continuous random variable B. Discrete random variable
C. Complement rule D. All of the above
19. Chances are 50-50 that a newborn baby will be a girl. For families with five children, what is the probability
that all the children are girls?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. 0.250
20. A new car was put into production. It involved many assembly tasks. Each car was inspected at the end of
the assembly line and the number of defects per unit was recorded. For the first 100 cars produced, there were
30 defective cars. Some of the cars had no defects; a few had one defect, and so on. The distribution of defects
followed a Poisson distribution. Based on the first 100 produced, about how many out of every 1,000 cars
assembled should have one or more defects?
A. About 660 B. About 165 C. About 260 D. About 330
21. A manufacturer of headache medicine claims it is 70 percent effective within a few minutes. That is, out of
every 100 users 70 get relief within a few minutes. A group of 12 patients are given the medicine. If the claim is
true, what is the probability that 8 have relief within a few minutes?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. 0.231
22. A true-false test consists of six questions. If you guess the answer to each question, what is the probability
of getting all six questions correct?
A. 0 B XXXXXXXXXXC XXXXXXXXXXD. 0.250
23. What is the only variable in the Poisson probability formula?
A. n B. x C. e D. P
24. In a Poisson distribution the mean is equal to
A. n? B. Σx/N C. e - x. D. µxe-µ/x!
25. The shape of any uniform probability distribution is
A. Negatively skewed B. Positively skewed C. Rectangular D. Bell shaped
26. The mean of any uniform probability distribution is
A. (b - a)/2 B. (a + b)/2 C. D. n
27. The standard deviation of any uniform probability distribution is
A. (b – a)/2 B. n ( 1 – ) C. D.
28. The upper and lower limits of a uniform probability distribution are
A. positive and negative infinity B. plus and minus three standard deviations.
C. 0 and 1 D. the maximum and minimum values of the random variable.
29. What is an important similarity between the uniform and normal probability distributions?
A. The mean, median and mode are all equal. B. The mean and median are equal
C. They are negatively skewed D. About 68% of all observations are within one standard
XXXXXXXXXXdeviation of the mean.
30. For the normal distribution, the mean plus and minus 1.96 standard deviations will include about what
percent of the observations?
A. 50% B. 99.7% C. 95% D. 68%
31. For a standard normal distribution, what is the probability that z is greater than 1.75?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD XXXXXXXXXX
32. What is the area under the normal curve between z = 0.0 and z = 2.0?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD XXXXXXXXXX
33. The mean amount spent by a family of four on food per month is $500 with a standard deviation of $75.
Assuming that the food costs are normally distributed, what is the probability that a family spends less than
$410 per month?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD XXXXXXXXXX
34. Which of the following is NOT a characteristic of the normal probability distribution?
A. Positively-skewed B. Bell-shaped C. Symmetrical D. Asymptotic
35. The mean of a normally distributed group of weekly incomes of a large group of executives is $1,000 and
the standard deviation is $50. What is the z-score for an income of $1,100?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. -0.90
36. Tables of normal distribution probabilities are found in many statistics books. These probabilities are
calculated from a normal distribution with
A. a mean of 1 and a standard deviation of 1 B. a mean of 100 and a standard deviation of 15
C. a mean of 0 and a standard deviation of 15 D. a mean of 0 and a standard deviation of 1
37. What is it called when all the items in a population have a chance of being selected in a sample?
A. Random sampling B. z-score C. Sampling error D. Nonprobability sampling
38. What is the difference between a sample mean and the population mean called?
A. Standard error of the mean B. Sampling error C. Interval estimate D. Point estimate
39. What sample statistic is used to estimate a population parameter?
A. Parameter B. Sampling error C. Point estimate D. Interval estimate
40. Suppose we select every fifth invoice in a file. What type of sampling is this?
A. Random B. Cluster C. Stratified D. Systematic
41. All possible samples of size n are selected from a population and the mean of each sample is determined.
What is the mean of the sample means?
A. Exactly the same as the population mean B. Larger than the population mean
C. Smaller than the population mean D. Cannot be estimated in advance
42. Based on the central limit theorem, the size of the sampling error is
A. Directly related to the sample size, i.e., the larger the sample size the larger the sampling error.
B. Directly related to the population mean, i.e., the larger the mean, the larger the sampling error
C. Inversely related to the sample size, i.e., the larger the sample size the smaller the sampling error.
D. Inversely related to the population standard deviation, i.e., the smaller the standard deviation, the larger the
43. For a distribution of sample means constructed by sampling 5 items from a population of 15,
A. the sample size is 15 B. there will be 3003 possible sample means
C. the mean of the sample means will be 3 D. the standard error will be 1
44. The wildlife department has been feeding a special food to rainbow trout fingerlings in a pond. A sample of
the weights of 40 trout revealed that the mean weight is 402.7 grams and the standard deviation 8.8 grams.
What is the probability that the mean weight for a sample of 40 trout exceeds 405.5 grams?
A XXXXXXXXXXB XXXXXXXXXXC. 1.0 D. 0.5
45. A statewide sample survey is to be made. First, the state is subdivided into counties. Seven counties are
selected at random and further sampling is concentrated on these seven counties. What type of sampling is this?
A. Simple random B. Nonproportional C. Cluster D. Stratified
46. Which of the following is the standard error of the mean?
A. B. x/n C. D. s
47. Sampling error is the difference between a corresponding sample statistic and the
A. sample mean. B. biased sample. C. population parameter. D. chance error.
48. For a population that is not normally distributed, the distribution of the sample means will
A. be negatively skewed. B. approach the normal distribution.
C. be positively skewed. D. take the same shape as the population.
Use the following to answer question 49:
Truck tire life is normally distributed with a mean of 60,000 miles and a standard deviation of 4,000 miles.
49. For a set of four tires, what is the probability that the average tire life is between 57,000 and 63,000 miles?
A XXXXXXXXXXB XXXXXXXXXXC XXXXXXXXXXD. very likely