# MA260 Online Exam 6_06 December 2015

Question

Online Exam 6_06

Question 1 of 40

2.5 Points

Based on meteorological records, the probability that it will snow in a certain town on January 1st is 0.413. Find the probability that in a given year it will not snow on January 1st in that town.

A. 0.345

B. 0.425

C. 0.587

D. 0.592

Question 2 of 40

2.5 Points

Suppose you have an extremely unfair die: The probability of a 6 is 3/8, and the probability of each other number is 1/8. If you toss the die 32 times, how many twos do you expect to see?

A. 2

B. 4

C. 3

D. 5

Question 3 of 40

2.5 Points

A committee of three people is to be formed. The three people will be selected from a list of five possible committee members. A simple random sample of three people is taken, without replacement, from the group of five people. Using the letters A, B, C, D, E to represent the five people, list the possible samples of size three and use your list to determine the probability that B is included in the sample. (Hint: There are 10 possible samples.)

A. 0.6

B. 0.4

C. 0.7

D. 0.8

Question 4 of 40

2.5 Points

A study of two types of weed killers was done on two identical weed plots. One weed killer killed 15% more weeds than the other. This difference was significant at the 0.05 level. What does this mean?

A. The improvement was due to the fact that there were more weeds in one study.

B. The probability that the difference was due to chance alone is greater than 0.05.

C. The probability that one weed killer performed better by chance alone is less than 0.05.

D. There is not enough information to make any conclusion.

Question 5 of 40

2.5 Points

Suppose you buy 1 ticket for $1 out of a lottery of 1000 tickets where the prize for the one winning ticket is to be $500. What is your expected value?

A. $0.00

B. ?$0.40

C. ?$1.00

D. ?$0.50

Question 6 of 40

2.5 Points

In the first series of rolls of a die, the number of odd numbers exceeded the number of even numbers by 5. In the second series of rolls of the same die, the number of odd numbers exceeded the number of even numbers by 11. Determine which series is closer to the 50/50 ratio of odd/even expected of a fairly rolled die.

A. The second series is closer because the difference between odd and even numbers is greater than the difference for the first series.

B. The first series is closer because the difference between odd and even numbers is less than the difference for the second series.

C. Since 1/2 > 1/5 > 1/11, the first series is closer.

D. The series closer to the theoretical 50/50 cannot be determined unless the total number of rolls for both series is given.

Question 7 of 40

2.5 Points

The data set represents the income levels of the members of a country club. Estimate the probability that a randomly selected member earns at least $98,000.

112,000 126,000 90,000 133,000 94,000 112,000 98,000 82,000 147,000 182,000 86,000 105,000

140,000 94,000 126,000 119,000 98,000 154,000 78,000 119,000

A. 0.4

B. 0.6

C. 0.66

D. 0.7

Question 8 of 40

2.5 Points

Joe dealt 20 cards from a standard 52-card deck, and the number of red cards exceeded the number of black cards by 8. He reshuffled the cards and dealt 30 cards. This time, the number of red cards exceeded the number of black cards by 10. Determine which deal is closer to the 50/50 ratio of red/black expected of fairly dealt hands from a fair deck and why.

A. The first series is closer because 1/10 is farther from 1/2 than is 1/8.

B. The series closer to the theoretical 50/50 cannot be determined unless the number of red and black cards for each deal is given.

C. The second series is closer because 20/30 is closer to 1/2 than is 14/20.

D. The first series is closer because the difference between red and black is smaller than the difference in the second series.

Question 9 of 40

2.5 Points

Suppose you have an extremely unfair coin: the probability of a head is 1/3 and the probability of a tail is 2/3. If you toss the coin 72 times, how many heads do you expect to see?

A. 12

B. 22

C. 24

D. 26

Question 10 of 40

2.5 Points

Jody checked the temperature 12 times on Monday, and the last digit of the temperature was odd six times more than it was even. On Tuesday, she checked it 18 times and the last digit was odd eight times more than it was even. Determine which series is closer to the 50/50 ratio of odd/even expected of such a series of temperature checks.

A. The Monday series is closer because 1/6 is closer to 1/2 than is 1/8.

B. The Monday series is closer because 6/12 is closer to 0.5 than is 8/18.

C. The Tuesday series is closer because the 13/18 is closer to 0.5 than is 9/12.

D. The series closest to the theoretical 50/50 cannot be determined without knowing the number of odds and evens in each series.

Question 11 of 40

2.5 Points

A die with 12 sides is rolled. What is the probability of rolling a number less than 11? Is this the same as rolling a total less than 11 with two six-sided dice? Explain.

A. 2/6

B. 3/6

C. 4/6

D. 5/6

No

Question 12 of 40

2.5 Points

Sammy and Sally each carry a bag containing a banana, a chocolate bar, and a licorice stick. Simultaneously, they take out a single food item and consume it. The possible pairs of food items that Sally and Sammy consumed are as follows.

chocolate bar – chocolate bar

licorice stick – chocolate bar

banana – banana

chocolate bar – licorice stick

licorice stick – licorice stick

chocolate bar – banana

banana – licorice stick

licorice stick – banana

banana – chocolate bar

Find the probability that no chocolate bar was eaten.

A. 4/9

B. 5/9

C. 7/9

D. 5/8

Question 13 of 40

2.5 Points

Of 1308 people who came into a blood bank to give blood, 314 people had high blood pressure. Estimate the probability that the next person who comes in to give blood will have high blood pressure (to 3 decimal places).

A. 0.250

B. 0.490

C. 0.240

D. 0.160

Question 14 of 40

2.5 Points

If you flip a coin three times, the possible outcomes are HHH, HHT, HTH,

HTT, THH, THT, TTH, TTT. What is the probability of getting at least one head?

A. 4/9

B. 5/6

C. 7/8

D. 5/8

Question 15 of 40

2.5 Points

A sample space consists of 46 separate events that are equally likely. What is the probability of each?

A. 1/24

B. 1/46

C. 1/32

D. 1/18

Question 16 of 40

2.5 Points

In a poll, respondents were asked whether they had ever been in a car accident. 220 respondents indicated that they had been in a car accident and 370 respondents said that they had not been in a car accident. If one of these respondents is randomly selected, what is the probability of getting someone who has been in a car accident? Round to the nearest thousandth.

A. 0.384

B. 0.380

C. 0.373

D. 0.370

Question 17 of 40

2.5 Points

A study of 600 college students taking Statistics 101 revealed that 54 students received the grade of A. Typically 10% of the class gets an A. The difference between this group of students and the expected value is not significant at the 0.05 level. What does this mean in this case?

A. The probability that the difference occurred due to chance is less than 0.05.

B. The probability of getting an A is 10% and only 9% got an A in this study. The difference is less than 5% so it is not significant.

C. There is not enough information to make any conclusion.

D. The probability that the difference occurred due to chance is more than 0.05.

Question 18 of 40

2.5 Points

Suppose you have an extremely unfair coin: the probability of a head is 1/5, and the probability of a tail is 4/5. If you toss the coin 40 times, how many heads do you expect to see?

A. 8

B. 6

C. 5

D. 4

Question 19 of 40

2.5 Points

A study of students taking Statistics 101 was done. Four hundred students who studied for more than 10 hours averaged a B. Two hundred students who studied for less than 10 hours averaged a C. This difference was significant at the 0.01 level. What does this mean?

A. The probability that the difference was due to chance alone is greater than 0.01.

B. There is less than a 0.01 chance that the first group’s grades were better by chance alone.

C. The improvement was due to the fact that more people studied.

D. There is not enough information to make any conclusion.

Question 20 of 40

2.5 Points

On a multiple choice test, each question has 6 possible answers. If you make a random guess on the first question, what is the probability that you are correct?

A. 1/5

B. 1/6

C. 1/4

D. 2/5

Question 21 of 40

2.5 Points

Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.

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A. 0.60

B. -0.97

C. 0.10

D. -0.60

Question 22 of 40

2.5 Points

Suggest the cause of the correlation among the data.

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A.

The variation in the x variable is a direct cause of the variation in

the y variable.

B. There is no correlation between the variables.

C. The correlation is due to a common underlying cause.

D. The correlation between the variables is coincidental.

Question 23 of 40

2.5 Points

Among a random sample of 500 college students, the mean number of hours worked per week at non-college related jobs is 14.6. This mean lies 0.4 standard deviations below the mean of the sampling distribution. If a second sample of 500 students is selected, what is the probability that for the second sample, the mean number of hours worked will be less than 14.6?

A. 0.5

B. 0.6179

C. 0.6554

D. 0.3446

Question 24 of 40

2.5 Points

Select the best fit line on the scatter diagram below.

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A. A

B. B

C. C

D. All of the lines are equally good

Question 25 of 40

2.5 Points

Select the best fit line on the scatter diagram below.

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A. A

B. B

C. C

D. None of the lines is the line of best fit

Question 26 of 40

2.5 Points

A researcher wishes to estimate the proportion of college students who cheat on exams. A poll of 490 college students showed that 33% of them had, or intended to, cheat on examinations. Find the margin of error for the 95% confidence interval.

A. 0.0432

B. 0.0434

C. 0.0425

D. 0.0427

Question 27 of 40

2.5 Points

Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.

.png”>

A. -0.9

B. 0.9

C. 0.5

D. -0.5

Question 28 of 40

2.5 Points

A sample of 64 statistics students at a small college had a mean mathematics ACT score of 28 with a standard deviation of 4. Estimate the mean mathematics ACT score for all statistics students at this college. Give the 95% confidence interval.

A. 28.0 to 30.0

B. 25.0 to 27.0

C. 29.0 to 31.0

D. 27.0 to 29.0

Question 29 of 40

2.5 Points

Among a random sample of 150 employees of a particular company, the mean commute distance is 29.6 miles. This mean lies 1.2 standard deviations above the mean of the sampling distribution. If a second sample of 150 employees is selected, what is the probability that for the second sample, the mean commute distance will be less than 29.6 miles?

A. 0.8849

B. 0.5

C. 0.1131

D. 0.1151

Question 30 of 40

2.5 Points

The scatter plot and best-fit line show the relation among the number of cars waiting by a school (y) and the amount of time after the end of classes (x) in arbitrary units. The correlation coefficient is -0.55. Use the line of best fit to predict the number of cars at time 4 after the end of classes.

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A. 7.0

B. 6.0

C. 8.0

D. 3.5

Question 31 of 40

2.5 Points

A random sample of 30 households was selected from a particular neighborhood. The number of cars for each household is shown below. Estimate the mean number of cars per household for the population of households in this neighborhood. Give the 95% confidence interval.

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A. 1.14 to 1.88

B. 1.12 to 1.88

C. 1.12 to 1.98

D. 1.14 to 1.98

Question 32 of 40

2.5 Points

The graph shows a measure of fitness (y) and miles walked weekly. Identify the probable cause of the correlation.

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A. The correlation is coincidental.

B. There is a common underlying cause of the correlation.

C. There is no correlation between the variables.

D. Walking is a direct cause of the fitness.

Question 33 of 40

2.5 Points

Write possible coordinates for the single outlier such that it would no longer be an outlier.

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A. (23, 18)

B. (20, 5)

C. (15, 15)

D. (12, 15)

Question 34 of 40

2.5 Points

A researcher wishes to estimate the proportion of college students who cheat on exams. A poll of 560 college students showed that 27% of them had, or intended to, cheat on examinations. Find the 95% confidence interval.

A. 0.2323 to 0.3075

B. 0.2325 to 0.3075

C. 0.2325 to 0.3185

D. 0.2323 to 0.3185

Question 35 of 40

2.5 Points

Which graph has two groups of data, correlations within each group, but no correlation among all the data?

A.

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B.

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C.

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D.

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Question 36 of 40

2.5 Points

Which point below would be an outlier if it were on the following graph?

.png”>

A. (25, 20)

B. (5, 12)

C. (7, 5)

D. (5, 3)

Question 37 of 40

2.5 Points

Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram.

.png”>

A. -0.9

B. 0.1

C. 0.5

D. 0.9

Question 38 of 40

2.5 Points

Monthly incomes of employees at a particular company have a mean of $5954. The distribution of sample means for samples of size 70 is normal with a mean of $5954 and a standard deviation of $259. Suppose you take a sample of size 70 employees from the company and find that their mean monthly income is $5747. How many standard deviations is the sample mean from the mean of the sampling distribution?

A. 0.8 standard deviations above the mean

B. 0.8 standard deviations below the mean

C. 7.3 standard deviations below the mean

D. 207 standard deviations below the mean

Question 39 of 40

2.5 Points

Which line of the three shown in the scatter diagram below fits the data best?

.png”>

A. A

B. B

C. C

D. All the lines are equally good

Question 40 of 40

2.5 Points

The scatter plot and best-fit line show the relation between the price per item (y) and the availability of that item (x) in arbitrary units. The correlation coefficient is -0.95. Determine the amount of variation in pricing explained by the variation in availability.

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A. 5%

B. 10%

C. 95%

D. 90%

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