Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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In a weight training class the mean
average weight for the bench press is 230 lbs. with a standard deviation of 5 lbs. If 10
students are chosen at random, determine the standard error.
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a. | 0.79 | c. | 3.65 | b. | 1.58 | d. | none of these |
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2.
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As the sample size increases for the study increases what happens to the size of
the confidence interval.
a. | The size of the confidence interval decreases. | b. | The size of the
confidence interval increases. | c. | The size of the confidence interval stays the
same. |
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3.
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What is the critical value,  , associated with a 99%
confidence interval?
a. | 0.990 | c. | 1.960 | b. | 1.645 | d. | 2.575 |
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4.
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A
mobile phone company determined with 95% confidence that the a teenager with a mobile phone send an
average of 180 text messages ± 20 messages each day.
Which of the following statement is
most likely to be true based on the study?
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a. | There is a 95% probability that every student with a mobile phone sends at least 160
messages a day.
| b. | There is a 95% probability that every student with a mobile phone sends at most 200
messages a day.
| c. | There is a 95% probability that the true average of text messages sent by a teenager
is somewhere between 160 and 200 text messages a day.
| d. | There is a 95% probability that the true
average of text messages sent by a teenager is 180 text messages a
day. |
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5.
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An
airline is trying to calculate an expected amount of baggage weight per passenger to predict fuel
expenses. Using a relatively large sample the airline determined that the sample mean for each
passenger was 34 pounds  of luggage with a standard error of 4 pounds,
 . Construct a 99% confidence interval that would describe the actual true average
weight of a passenger’s luggage weight. | | | |
a. | With 99 % confidence the true average weight of a passenger’s luggage is
between 30 and 38 pounds.
| b. | With 99 % confidence the true average
weight of a passenger’s luggage is between 27.42 and 40.58
pounds.
| c. | With 99 % confidence the true average weight of a passenger’s luggage is
between 26.16 and 41.84 pounds.
| d. | With 99 % confidence the true average
weight of a passenger’s luggage is between 23.7 and 44.3
pounds.
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6.
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A high school administrator
determined at 99% confidence level that 22% of the students worked part-time after school with a
±8% margin of error.
If the school has 1420 students, which would represent the
possible number of students that work part-time after school?
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a. | 199 to 426 students | c. | 195 to 430 students | b. | 114 to 312 students | d. | 47 to 178
students |
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7.
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A printer cartridge company claims their ink lasts for more than 5,000
words. The number of words printed is normally distributed with a standard deviation of 20
(  ) A
sample was taken of 50 cartridges and it was found that they had a mean of 4,940 words. Construct a
95% confidence interval (z = 1.96).
Using the interval does the company’s claim hold
true?
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a. | No, the companies claims are above the 95% confidence interval.
| c. | No, the companies
claims are below the 95% confidence interval. | b. | Yes, the companies claims fall within the 95%
confidence interval.
| d. | Yes,
the companies claims are below the 95% confidence interval. |
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8.
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The store Better Buys knows that the
cost to repair a computer is normally distributed with a standard deviation of $40 ( ).
A random sample of 10 computer repairs and found the average of those 10 computer repairs was
$154. Construct a 95% confidence interval of the population mean of a computer repair.
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9.
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An
admissions director wants to estimate the mean age of all students enrolled at a college. The
estimate must be within 1 year. The ages are not normally distributed so the director knows she will
need a sample of at least 30.
Determine the minimum required sample size to construct a 99%
confidence interval for the population mean. Assume the population standard deviation is 4.8
years ( ).
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a. | n = 48 | c. | n = 114 | b. | n = 62 | d. | n = 153 |
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