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Unformatted text preview: ch of the following statements about the binomial distribution is not correct?
A. Each trial results in a success or failure.
B. Trials are independent of each other.
C. The probability of success remains constant from trial to trial.
D. The random variable of interest is continuous.
E. The experiment consists of n identical trials. 31. If n = 20 and p = .4, then the mean of the binomial distribution is
A. .4
B. 4.8
C. 8
D. 12 32. If n = 15 and p = .4, then the standard deviation of the binomial distribution is
A. 9
B. 6
C. 3.6
D. 1.8974
E. .4 1356 Chapter 01  An Introduction to Business Statistics 33. The equation for the variance of the binomial distribution is given by:
A. px (1  p)nx
B. np
C. np (1p)
D. 34. The manager of the local grocery store has determined that, on the average, 4 customers
use the service desk every halfhour. Assume that the number of customers using the service
desk has a Poisson distribution.
What is the probability that during a randomly selected halfhour period exactly 2 customers
use the service desk?
A. .0183
B. .0733
C. .1465
D. .9084
E. .7619 35. The manager of the local grocery store has determined that, on the average, 4 customers
use the service desk every halfhour. Assume that the number of customers using the service
desk has a Poisson distribution.
What is the probability that during a randomly selected halfhour period no more than 2
customers use the service desk?
A. .2381
B. .1465
C. .7619
D. .8535
E. .0916 36. The probability that a given computer chip will fail is 0.02. Find the probability that of 5
delivered chips, exactly 2 will fail.
A. .9039
B. .0922
C. .0038
D. .0000 1357 Chapter 01  An Introduction to Business Statistics 37. According to a survey of adults, 64% have money in a regular savings account. If we plan
on surveying 50 randomly selected adults, find the mean number of adults who would have
regular savings accounts.
A. 12
B. 22
C. 32
D. 42 38. In the most recent election, 19% of all eligible college students voted. If a random sample
of 20 students were surveyed:
Find the probability that exactly half voted in the election.
A. .0000
B. .0014
C. .0148
D. .4997 39. In the most recent election, 19% of all eligible college students voted. If a random sample
of 20 students were surveyed:
Find the probability that none of the students voted.
A. .0000
B. .0014
C. .0148
D. .4997 40. Of all individual tax returns, 37% include errors made by the taxpayer. If IRS examiners
are assigned randomly selected returns in batches of 12, find the mean and standard deviation
for the number of erroneous returns per batch.
A. = 2.80,
= 1.67
B. = 4.44,
= 1.67
C.
= 4.44,
= 2.80
D. = 7.56,
= 2.80 1358 Chapter 01  An Introduction to Business Statistics 41. In a study conducted for the State Department of Education, 30% of the teachers who left
teaching did so because they were laid off. Assume that we randomly select 10 teachers who
have recently left their profession. Find the probability that exactly 4 of them were laid off.
A. .3000
B. .2668
C. .2001
D. .0090 42. A company manufactures an appliance, gives a warranty and 95% of its appliances do not
require repair before the warranty expires. If an organization buys 10 of these appliances,
calculate an interval that contains 95.44% of all the appliances that won't require repair.
A. [8.12 10.88]
B. [7.43 11.57]
C. [8.81 10.19]
D. [8.55 10.45] 43. A manufacturer tested a sample of semiconductor chips and found that 35 were defective
and 190 were good. If additional tests are to be conducted with random samples of 160
semiconductor chips, find the mean for the number of defects in these groups of 160 (rounded
to nearest whole number).
A. 56
B. 35
C. 29
D. 25 44. In a study conducted by UCLA, it was found that 25% of college freshmen support
increased military spending. If 6 college freshmen are randomly selected, find the probability
that:
Fewer than 4 support increased military spending
A. .0330
B. .7844
C. .9624
D. .9954 1359 Chapter 01  An Introduction to Business Statistics 45. In a study conducted by UCLA, it was found that 25% of college freshmen support
increased military spending. If 6 college freshmen are randomly selected, find the probability
that: Exactly 3 support increased military spending
A. .0330
B. .1318
C. .7844
D. .9624 46. In a study conducted by UCLA, it was found that 25% of college freshmen support
increased military spending. If 6 college freshmen are randomly selected, find the probability
that: Only 1 support increased military spending
A. .0330
B. .1318
C. .3560
D. .7844 47. A multiplechoice test has 30 questions and each one has five possible answers, of which
one is correct. If all answers were guesses, find the probability of getting exactly four correct
answers.
A. .0604
B. .1325
C. .2552
D. .8000 48. It is known that 15% of all college freshmen at Ivey University leave after their first year.
Calculate the interval that contains 99.73% of the students who remain if we are lookin...
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