Download A MULTIPLE CHOICE. Choose the one alternative that best

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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) An auto salesperson sells an average of 2 cars per day. Let x be the number of cars sold by this salesperson on
any given day. Find the mean and standard deviation of x
A) 2 and 2
B) 2 and 4
C) 2 and 1.414
D) None of the above .
2) For some positive value of X, the probability that a standard normal variable is between 0 and +2X is 0.1255.
What is the value of X?
A) 0.32
B) 0.16
C) 0.99
D) 0.40
3) You were told that the mean score on a statistics exam is 75 with the scores normally distributed. In addition,
you know the probability of a score between 55 and 60 is 4.41% and that the probability of a score greater than
90 is 6.68%. What is the probability of a score greater than 95?
A) 0.0338
B) 0.0238
C) 0.0138
D) None of the above .
4) Which of the following is not a characteristic of the normal distribution?
A) Mean=median=mode
B) Symmetric
C) Bell-shaped
D) Equal probabilities at all values of x
5) A seafood shop sells salmon fillets where the weight of each fillet is normally distributed with a mean of 1.6
pounds and a standard deviation of 0.3 pounds. Based on this information we can conclude that 50 % of the
fillets weight is less __________ pound.
A) 1
B) 1.6
C) 1.7
D) Between 1.6 to 1.7
6) The assembly time of a toy follows a normal distribution with a mean of 80 minutes and a standard deviation
of 10 minutes. The company closes at 5 P.M. every day. If one worker starts assembling the toy at 3:30 P.M.,
what is the probability that she will finish this job before the company closes for the day?
A) She will definitely finish
B) 0.8413
C) 0.3438
D) 0.3413
7) The amount of time necessary for assembly line workers to complete a product is a normal random variable
with a mean of 15 minutes and a standard deviation of 2 minutes. So, 93 % of the products would be assembled
within ________ minutes.
A) 15
B) 16
C) 17
D) 18
8) The owner of a fish market determined that the average weight for a catfish is 3.2 pounds with a standard
deviation of 0.8 pound. A citation catfish should be one of the top 2% in weight. Assuming the weights of
catfish are normally distributed, at what weight (in pounds) should the citation designation be established?
A) 5.20 pounds
B) 4.84 pounds
C) 7.36 pounds
D) 1.56 pounds
9) Which is bigger, a circle or a square
A) Circle
B) Square
C) Donʹt choose me, Iʹm not the answer
D) Canʹt be determined without more information.
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10) The manager at a local movie theater has collected data for a long period of time and has concluded that the
revenue from concession sales during the first show each evening is normally distributed with a mean equal to
$336.25 and a variance equal to 1,456. Based on this information, what are the chances that the revenue on the
first show will exceed $800?
A) 0.9999
B) 0.3745
C) Essentially zero
D) 0.1255
11) Suppose the GMAT scores of all students have a normal distribution with a mean of 550 and a standard
deviation of 100. Matt Sanger is planning to take this test soon. What should his score be on this test so that
only 5% of all the examinees score higher than he does?
A) 500
B) 660
C) 700
D) 715
12) If a particular batch of data is approximately normally distributed, we would find that approximately
A) 3 of every 5 observations would fall between ±1.28 standard deviations around the mean.
B) 2 of every 3 observations would fall between ±1 standard deviation around the mean.
C) 12 of every 20 observations would fall between ±2 standard deviations around the mean.
D) all of the above
13) A catalog company that receives the majority of its orders by telephone conducted a study to determine how
long customers were willing to wait on hold before ordering a product. The length of time was found to be a
random variable best approximated by an exponential distribution with a mean equal to 3 minutes. What
proportion of customers having to hold more than 4.5 minutes will hang up before placing an order?
A) 0.48658
B) 0.22313
C) 0.51342
D) 0.77687
14) For some positive value of Z, the probability that a standard normal variable is between 0 and Z is 0.4505. What
is the value of Z?
A) 1.65
B) 0.37
C) 1.06
D) 0.97
15) A class takes an exam where the average time to complete the exam is normally distributed with a 45 minutes
and standard deviation of 10 minutes. If the class lasts 1 hour, what percent of the students will have turned in
the exam after 60 minutes?
A) 0.4332
B) 0.9332
C) 0.0668
D) 0.5668
16) A catalog company that receives the majority of its orders by telephone conducted a study to determine how
long customers were willing to wait on hold before ordering a product. The length of time was found to be a
random variable best approximated by an exponential distribution with a mean equal to 3 minutes. Find the
waiting time at which only 10% of the customers will continue to hold.
A) 6.9 minutes
B) 3.3 minutes
C) 2.3 minutes
D) 13.8 minutes
17) In its standardized form, the normal distribution
A) has a mean of 1 and a variance of 0.
B) has an area equal to 0.5.
C) has a mean of 0 and a standard deviation of 1.
D) cannot be used to approximate discrete probability distributions.
18) If we know that the length of time it takes a college student to find a parking spot in the library parking lot
follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the
probability that a randomly selected college student will find a parking spot in the library parking lot in less
than 2 minutes.
A) 0.0668
B) 0.3085
C) 0.1915
D) 0.2674
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19) The probability that a standard normal random variable, Z, falls between -.50 and 0.85 is
A) 0.1108
B) 0.3023
C) 0.4938
D) 0.1915
20) Students who have completed a speed reading course have reading speeds that are normally distributed with a
mean of 1000 words per minute and a standard deviation equal to 250 words per minute. If the two students
were selected at random, what is the probability that they would both read at less than 400 words per minute?
A) 0.0228
B) 0.00004
C) 0.4772
D) 0.0005
21) The average number of traffic accidents on a certain section of highway is two per week. Assume that the
number of accidents follows a Poisson distribution, what is the probability of at most 2 accidents per month
A) 0.0137
B) 0.0107
C) .0027
D) 0.6767
22) The manager of a computer help desk operation has collected enough data to conclude that the distribution of
time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14
minutes. What is the probability that three randomly monitored calls will each be completed in 4 minutes or
less?
A) About 0.00001
B) 0.4756
C) Approximately 0.1076
D) Canʹt be determined without more information.
23) Which of the following about the normal distribution is not true?
A) Theoretically, the mean, median, and mode are the same.
B) About 2/3 of the observations fall within ±1 standard deviation from the mean.
C) Its parameters are the mean, μ, and standard deviation, σ.
D) It is a discrete probability distribution.
24) The number of visible defects on a product container is thought to be Poisson distributed with a mean equal to
3.5. Based on this, the probability that 2 containers will contain a total of less than 2 defects is:
A) 0.0073.
B) 0.1359.
C) 0.0223.
D) 0.1850.
25) Do you like the way I teach?
A) Certainly yes
B) Definitely yes
C) Surely yes
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D) Absolutely yes
Answer Key
Testname: QUIZ4A
1) C
2) B
3) D
4) D
5) B
6) B
7) D
8) B
9) D
10) C
11) D
12) B
13) B
14) D
15) B
16) A
17) C
18) A
19) C
20) D
21) A
22) A
23) D
24) A
25) A
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