Statistics Homework Help

Question 6 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

What is the variance of X?

A.2.50

B.3.42

C.4.32

D.2.34

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Part 4 of 9 –

Question 7 of 25 1.0 Points

The theorem that states that the sampling distribution of the sample mean is approximately normal when

the sample size n is reasonably large is known as the:

A.central tendency theorem

B.central limit theorem

C.simple random sample theorem

D.point estimate theorem

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Question 8 of 25 1.0 Points

If Z is a standard normal random variable, the area between z = 0.0 and z =1.30 is 0.4032, while the area

between z = 0.0 and z = 1.50 is 0.4332. What is the area between z = -1.30 and z = 1.50?

A.0.0668

B.0.0300

C.0.8364

D.0.0968

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Question 9 of 25 1.0 Points

If the value of the standard normal random variable Z is positive, then the original score is where in

relationship to the mean?

A.to the right of the mean

B.equal to the mean

C.to the left of the mean

D.one standard deviation higher than the mean

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Question 10 of 25 1.0 Points

Find the probability, P(Z < 0.17), using the standard normal distribution.

A..8300

B..4325

C..5675

D..0675

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Question 11 of 25 1.0 Points

The mean of a probability distribution can be:

A.a positive number

B.a negative number

C.zero

D.all of the above

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Question 12 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.0.3764

B.1.16

C.1.54

D.3.08

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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 above 50? 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(1 < X < 5). 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.

According to an Internet posting, 80% of adults enjoy drinking beer. If a group of 3 adults is selected at

random, find the probability that none of them enjoy drinking beer.

Place your answer, rounded to three decimal places, in the blank. When

entering your answer do not use any labels or symbols other than a decimal point.

Simply provide the numerical value. For example, 0.123 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.

Suppose that the average weekly earnings for employees in general automotive repair shops is $450,

and that the standard deviation for the weekly earnings for such employees is $50. A sample of 100 such

employees is selected at random.

Find the standard deviation of the sampling distribution of the means of average weekly earnings for

samples of size 100. Place your answer in the blank. Do not include a dollar sign. For example, 7 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.

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 90% 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 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 set of final exam scores in an organic chemistry course was found to be normally distributed, with a

mean of 73 and a standard deviation of 8.

What is the probability of getting a score of 91 or less on this exam? Place your answer, rounded to 4

decimal places in the blank. For example, 0.3456 would be a legitimate entry.

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 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 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.

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 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.

A set of final exam scores in an organic chemistry course was found to be normally distributed, with a

mean of 73 and a standard deviation of 8.

What is the probability of getting a score higher than 71 on this exam? Place your answer, rounded to 4

decimal places in the blank. For example, 0.3456 would be a legitimate entry.

Part 9 of 9 –

Question 24 of 25 1.0 Points

If Z is a standard normal variable, then P(Z > 1.50) = 0.9332

True

False

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Question 25 of 25 1.0 Points

Using the standard normal curve, the Z- score representing the 85th percentile is 0.67

True

False

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