# Statistics Quiz

MATH311
Statistics Quiz
Question 1 of 25
1.0
Points
Which of the following correctly
describes the relationship between a sample and a population?
A.A
population is a group of samples that may or may not be included in a
study
B.A
sample is a group of subjects selected from a population to be studied.
C.A
sample is a group of populations that are subject to observation.
D.A
population and a sample are not related.
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Part 2 of 9 –
Question 2 of 25
1.0
Points
The probability of an event and
the probability of its complement always sum to:
A.any
value between 0 and 1
B.any
positive value
C.0
D.1.0
Reset SelectionQuestion 3 of 25
1.0
Points
Three cards are drawn from a
deck without replacement. What is the probability that all three cards are
clubs?
A.0.25
B.0.0156
C.0.0129
D.0.012
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Part 3 of 9 –
Question 4 of 25
1.0
Points
The following data were obtained
from a survey of college students. The variable X represents
the number of non-assigned books read during the past six months.
x
0
1
2
3
4
5
P (X=x)
0.20
0.25
0.20
0.15
0.10
0.10
Find P( X > 1) A.0.55 B.0.80 C.0.20 D.0.45 Reset Selection Question 5 of 25
1.0
Points
Find the variance of the following probability
distribution. X P(X) 1 0.10 2 0.35 3 0.10 4 0.15 5 0.30 A.1.44 B.2.06 C.1.76 D.1.2 Reset Selection Question 6 of 25
1.0
Points
In a small town, 60% of the
households have dogs. If 5 households are randomly selected, what is the
probability that at least 4 of them have dogs?
A.0.8
B.0.337
C.0.259
D.3
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Part 4 of 9 –
Question 7 of 25
1.0
Points
The standard deviation of a
probability distribution must be:
A.a
negative number
B.a
nonnegative number
C.less
than the value of the mean
D.a
number between 0 and 1
Reset SelectionQuestion 8 of 25
1.0
Points
In a normal distribution,
changing the standard deviation:
A.splits
the distribution to two curves
B.makes
the curve more or less spread out
C.shifts
the curve left or right
D.makes
the curve more robust
Reset SelectionQuestion 9 of 25
1.0
Points
If Z is a standard normal random
variable, then the value z for which P(-z < Z < z) equals 0.8764 is
A.1.16
B.1.54
C.3.08
D.0.3764
Reset SelectionQuestion 10 of
25
1.0
Points
The average height of flowering
cherry trees in a nursery is 11 feet. If the heights are normally
distributed with a standard deviation of 1.6, find the probability that a
randomly selected cherry tree in this nursery is less than 13 feet tall.
A. 0.67
B.0.89
C.0.95
D.0.11
Reset SelectionQuestion 11 of
25
1.0
Points
The standard deviation of a
probability distribution is a:
A.measure
of skewness of the distribution
B.measure
of variability of the distribution
C.measure
of relative likelihood
D.measure
of central location Reset Selection Question 12 of
25
1.0
Points
The normal distribution is:
A.a
discrete distribution
B.a
binomial distribution with only one parameter
C.a
density function of a discrete random variable
D.the
single most important distribution in statistics
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Part 5 of 9 –
Question 13 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The histogram below represents scores achieved by 250 job applicants on a personality profile. How many job applicants scored between 10 and 30? Place your answer in the blank. Do not use any stray symbols. For example, 123 would be a legitimate answer. |

Part 6 of 9 –
Question 14 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. In a survey, 55% of the voters support a particular referendum. If 40 voters are chosen at random, and X is the number of voters that support this referendum, find the mean and variance of X. Place the mean in the first blank and place the variance in the second blank. Question 15 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The following data were obtained from a survey of college students. The variable X represents
the number of non-assigned books read during the past six months.
x
0
1
2
3
4
5
6
P (X=x)
0.55
0.15
0.10
0.10
0.04
0.03
0.03
Find P(X 2). Place your answer, rounded to two decimal places in the blank. For example, 0.56 would be a legitimate entry. |

Part 7 of 9 –
Question 16 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The Big Triple at the local racetrack consists of picking the correct order of finish of the first three horses in the ninth race. If there are 12 horses entered in today’s ninth race, how many Big Triple outcomes are possible? Place your answer, as a whole number—no decimal places—in the blank. For example 667 would be a legitimate entry. Question 17 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. Mothers Against Drunk Driving (MADD) is a very visible group whose main focus is to educate the public about the harm caused by drunk drivers. A study was recently done that emphasized the problem we all face with drinking and driving. Five hundred accidents that occurred on a Saturday night were analyzed. Two items noted were the number of vehicles involved and whether alcohol played a role in the accident. The numbers are shown below:
Number of Vehicles Involved
Did
alcohol play a role?
1
2
3
Yes
60
110
30
200
No
40
215
45
300
100
325
75
What proportion of accidents involved alcohol and a
single vehicle?
Place your answer, rounded to 2 decimal places, in the
blank. For example, 0.23 is a legitimate entry. |

Part 8 of 9 –
Question 18 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. Mrs. Smith’s reading class can read a mean of 175 words per minute with a standard deviation of 20 words per minute. The top 3% of the class is to receive a special award. Assuming that the distribution of words read per minute are normally distributed, what is the minimum number of words per minute a student would have to read in order to get the award? Place your answer, rounded to the nearest whole number,
in the blank. When
entering your answer do not use any labels or symbols. Simply provide
the numerical value. For example, 123 would be a legitimate
entry. Question 19 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. Scores on a mathematics examination appear to follow a normal distribution with mean of 65 and standard deviation of 15. The instructor wishes to give a grade of “C” to students scoring between the 60th and 70th percentiles on the exam. What score represents the 60th percentile score on the mathematics exam? Place your answer in the blank, rounded to a whole number. For example, 62 would be a legitimate entry. Question 20 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. A popular retail store knows that the purchase amounts by its customers is a random variable that follows a normal distribution with a mean of $30 and a standard deviation of $9. What are the two dollar amounts, equidistant from the mean of $30, such that 98% of all customer purchases are between these values? Place your answers in the blanks provided. Do not include a dollar sign. For example, 14.25 would be a legitimate entry. Lower value Upper value Question 21 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The average hourly wage of workers at a fast food restaurant is $6.50/hr with a standard deviation of $0.45. Assume that the distribution is normally distributed. If a worker at this fast food restaurant is selected at random, what is the probability that the worker earns more than $6.75? Place your answer, rounded to 4 decimal places, in the blank. For example, 0.1776 would be a legitimate entry. Question 22 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. The length of time to complete a door assembly on an automobile factory assembly line is normally distributed with mean 6.7 minutes and standard deviation 2.2 minutes. For a door selected at random, what is the probability the assembly line time will be between 5 and 10 minutes? Place your answer, rounded to 4 decimal places, in the blank. For example, 0.1776 would be a legitimate answer. Question 23 of
25
1.0
Points
Accepted characters: numbers, decimal point markers (period or comma), sign
indicators (-), spaces (e.g., as thousands separator, 5 000), “E”
or “e” (used in scientific notation). NOTE: For
scientific notation, a period MUST be used as the decimal point
marker. Complex numbers should be in the form (a + bi) where “a” and “b” need to have explicitly stated values. For example: {1+1i} is valid whereas {1+i} is not. {0+9i} is valid whereas {9i} is not. It has been observed that electrical connectors manufactured by Jolt Electrical Supply Company last an average of 18.2 months and follow a normal distribution with a standard deviation of 1.7 months. Jolt agrees to replace any connector that fails within 19 months. Out of 500 connectors sold, how many does Jolt expect to replace, on average? Place your answer, rounded to the nearest whole number, in the blank. For example, 123 would be a legitimate answer. |

Part 9 of 9 –
Question 24 of
25
1.0
Points
The sampling distribution of the
mean will have the same mean as the original population from which the
samples were drawn.
True
False
Reset SelectionQuestion 25 of
25
1.0
Points
Using the standard normal curve,
the Z- score representing the 99th percentile is 2.326.
True
False |

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