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1. A sample of 20 employee’s salaries from a large company results in the following salaries (in thousands of dollars) for this year. 28 31 34 35 37 47 42 42 49 41 42 60 52 52 51 72 67 61 75 77.

What is the interquartile range (in thousands) of this data set? (A) 21. 5 (B) 10 (C) 50 (D) 23 (E) correct answer is not given 2. Please refer to the previous question. Suppose each employee in the company receives $3,000 raise for next year. The interquartile range (IQR) of the salaries will: (A) be unchanged (B) be multiplied by $3,000 (C) increase by $3,000 (D) decrease by $3,000 3.An HIV test has a 9% chance of indicating a false positive and 0. 5% chance of indicating a false negative.

This test is administered to a population of 1000 patients, 6 of whom are actually infected. If a patient is tested positive, what is the probability that he actually is infected? (A) 0. 93 (B) 0. 83 (C) 0. 063 (D) 0. 0587 4.

A study shows that employees that begin their work day at 9:00 a. m. vary their times of arrival uniformly from 8:40 a.

m. to 9:30 a. m. The probability that a randomly chosen employee reports to work between 9:00 and 9:10 is: (A) 40% (B) 20% (C)10% (D) 30% (E)16. % 5.

If A and B are events such that P(A) = 0. 20, P(B) = 0. 40. Assuming that A and B are independent, what is the probability that none of these two events occur? (A) 0. 40 (B) 0.

60 (C) 0. 52 (D) 0. 48 6.

Suppose that the wages of workers for a given company are normally distributed with a mean of $15 per hour. When we consider the proportion of the workers earning more than $13 per hour, we see that: (A) it is less than the proportion earning less than $13 per hour. (B) it is greater than the proportion earning less than $18 per hour. (C) it is less than 50%. D) it is less than the proportion earning more than the mean wage. (E) none of the above statements are correct.

2 7. An Introductory statistics class has 45 students. You want to call an SRS (simple random sample) of 5 students from the class to ask if they feel they’re well prepared for this exam. You label the students 01, 02,…, 45. Suppose that you enter a table of random digits at this line: 14459 26056 31421 40371 65103 62253 22490 61181 Your SRS contains the students labeled: (A) 14, 45, 92, 60, 56 (B) 14, 31, 03, 10, 22 (C) 14, 03, 10, 22, 22 (D) 14, 45, 31, 42, 03 (E) 14, 45, 31, 42, 14 8.According to astrological tradition people with birthdays between September 23 and October 22, inclusive, are born under the Zodiac sign “Libra”.

A randomly selected person was born in a non-leap year (365 day) year. What is the probability that she was born in October or is a “Libra”? (A) 0. 0603 (B) 0. 1068 (C) 0. 1671 (D) 0.

2274 (E) 0. 0000 9. The mean life of pair of shoes is 40 months with a standard deviation of 8 months. If the life of the shoes is normally distributed, how many pairs of shoes out of one million would we expect will need replacement before 36 months? (A) 500,000 (B) 808,500 (C) 191,500 (D) 308,500 (E) 705,100 0.

The letter grade that you receive on this test (i. e. A, B, etc. ) is an example of a(n): (A) nominative variable (B) ordinal variable (C) interval variable (D) ratio variable 11.

A particular characteristic of a unit of a population is an example of a(n): (A) variable (B) observation (C) measurement (D) statistic 3 12. The weather office forecast and actual weather for London is summarized in the following table. Rain No rain Total Forecast: Rain 66 156 Forecast: No Rain 14 Total 80 1,000 What percentage of the time was the weather office correct? (A) 6. 6% (B) 76.

4% (C) 83% (D) 92% 13.The _____________distribution would most likely be used to describe the distribution of arrivals to a grocery store and the _____________ distribution would most likely be used to describe the time between arrivals of customers to the grocery store. (A) Binomial, Normal (B) Poisson, Exponential (C) Normal, Binomial (D) Exponential, Poisson (E) Binomial, Poisson 14. Which of the following statements are true? (I) Mutually exclusive events are always independent. (II) Dependent events are always mutually exclusive. (III) For two dependent events A and B, P(A? B)=P(A)P(B|A) (A) Only (I) is correct.

B) Only (I) and (III) are correct. (C) Only (III) is correct. (D) Only (II) and (III) are correct. 15. The cashier service time at a local bank has an exponential distribution with a mean of 2. 5 minutes. What is the probability that the service time is between 2 and 4 minutes? (A) 0.

2488 (B) 0. 4493 (C) 0. 2019 (D) 0. 2474 (E) 0.

1170 16. A random variable X follows an exponential distribution with a standard deviation of 0. 5. What is P(X ? 0. 5)? (A) 0.

6321 (B) 0. 5 (C) 0. 3679 (D) 0. 7788 (E) 0. 2212 4 17. You are given the following summary statistics for a sample of 50 observations: Mean = 37 5th percentile = 36 Minimum = 24 Median = 44 Range = 28 IQR = 12 Are there any outliers in this sample? (A) Yes, all observations less than 36 (B) No.

(C) Yes, all observations greater than 48. (D) Yes, all observations less than 44. (E) Need more information.

18. A college basketball player fails to make 40% of his free throws. Over the course of the next month’s games, he will attempt 10 free throws.

Assuming free throw attempts are independent, what is the probability that he makes at least 9 of these attempts? (A) 0. 0403 (B) 0. 400 (C) 0. 0017 (D) 0. 0464 19. The probability that an appliance is in repair is 0. .

If an apartment complex has 100 such appliances, what is the probability that at least 60 will be in repair? Use the normal approximation to the binomial. (A) 0. 0228 (B) 0.

9821 (C) 0. 2019 (D) 0. 0287 (E) 0.

9772 20. Which of the following is a unique characteristic of an interval variable? (A) meaningful ratio (B) no meaningful zero (C) categorical in nature (D) qualitative (E) none of the above 21. A manufacturing company measures the weight of boxes before shipping them to its customers. The box weights have a population mean of 90 kg and standard deviation of 24 kg.If a random sample of size of 36 is taken, what is the probability that the mean of the sample of boxes will exceed 94 kg? (A) 34.

13% (B) 84. 13% (C) 15. 87% (D) 56. 36% (E) 16. 87% 5 22. A random variable “X” has a distribution represented by the following probability distribution xi P (X= xi) -1 3c 0 2c 2 2c 4 c where “c” is a constant real number.

The variance of the random variable “X” is (A) 191 64 (B) 27 8 (C) 4 (D) can not be determined from the given information. 23. In a statistic class, 10 scores were randomly selected with the following results were obtained: 74, 73, 77, 77, 71, 68, 65, 77, 67, 66What is the median of the sample? (A) 71. 5 (B) 72. 0 (C) 77.

0 (D) 71. 0 (E) 73. 0 24. A computer salesman sells computers at a rate of 0. 5 computers per day. What is the probability that, in any 7 day week, the salesman will sell 2 or more computers? (A) 0.

864 (B) 0. 09 (C) 0. 679 (D) 0.

014 (E) 0. 315 25. All human blood can be “ABO” typed as belonging to one of A, B, O, or AB types.

The actual distribution varies slightly among different groups of people, but for a randomly chosen person from North America, the following are the approximate probabilities: Blood Type Probability O 0. 5 A 0. 40 B 0. 11 AB c Here c is a constant real number.

What is the probability that both people in a couple will have the SAME blood type assuming one partner’s blood type does not influence the blood type of the other partner. (A) about 0. 21 (B) about 0.

16 (C) about 0. 04 (D) about 0. 38 (E) not enough information 6 26.

The internal auditing staff of a local manufacturing company perform a sample audit each quarter to estimate the proportion of accounts that are delinquent. The historical records of the company show that over the past 8 years 13 percent of the accounts are delinquent.For this quarter, the auditing staff randomly selected 250 customer accounts.

What is the probability that no more than 40 accounts will be classified as delinquent? (A) 42. 07 % (B) 92. 07 % (C) 7.

93 % (D) 40. 15 % (E) 90. 15% 27. An airplane is only allowed a gross passenger weight of 8,000 kg.

If the weights of passengers traveling by air between Toronto and Vancouver have a mean of 78 kg and a standard deviation of 7 kg, the approximate probability that the combined weight of 100 passengers will exceed 8,000 kg is: (A) 0. 6141 (B) 0. 3859 (C) 0. 1103 (D) 0.

0042 (E) 0. 0021 28. Suppose we wish to perform two separate experiments.

We wish to flip a fair coin n = 20 times and n = 100 times. We are interested in the probabilities of obtaining EXACTLY the same number of heads and tails in each experiment. What can we say about these probabilities? (A) They are both equal to 50%. (B) The probability is greater when n = 20. (C) The probability is greater when n = 100.

(D) They are both equal but less than 50%. (E) They are both equal but greater than 50%. 29. The probability that the Red River will flood in any given year has been estimated from 200 years of historical data to be one in four. This means: (A) The Red River will flood every four years. B) In the next 100 years, the Red River will flood exactly 25 times.

(C) In the last 100 years, the Red River flooded exactly 25 times. (D) In the next 100 years, the Red River will flood about 25 times. (E) In the next 100 years, it is very likely that the Red River will flood exactly 25 times.

30. Let x be the yearly proportional return for stock A, and let y be the yearly proportional return for stock B. If ? = x 0.

11, ? = y 0. 09, x ? =0. 14, y ? =0.

17, and ? = xy -0. 0212, find the standard deviation of the portfolio return P =0. 6x+0. 4y.

(A) 0. 0015 (B) 0. 3859 (C) 0. 1103 (D) 0. 0042 (E) 0. 0388

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