Devry MATH221 All Weeks Quizzes Latest 2019 JULY

MATH221 Statistics for Decision Making

Week 3 Quiz

Question 1 (CO 1) Among 500 people at the concert, a survey of 35 found 28% found it too loud. What is the population and what is the sample?

Population: 500 at that concert; Sample: the 35 in the survey

Population: all concert goers; Sample: the 28% who found it too loud

Population: 500 at that concert: Sample: the 28% who found it too loud

Population: all concert goers; Sample: the 500 at that concert

Question 2(CO 1) A survey of 481 of your customers shows that 79% of them like the recent changes to the product. Is this percentage a parameter or a statistic and why?

Parameter as it represents the sample

Statistic as it represents the population

Parameter as it represents the population

Statistic as it represents the sample

Question 3(CO 1) Classify the data of the top grossing movies for 2017.

Statistics

Qualitative

Quantitative

Classical

Question 4(CO 1) The data set that lists the number of performances for each Broadway show in 2017 would be classified as what type of data?

Ratio

Nominal

Interval

Ordinal

Question 5(CO 1) A data set that includes the number of products that were produced within each hour by a company would be classified as what type of data?

Ordinal

Ratio

Nominal

Interval

Question 6(CO 1) What type of data collection might be best to estimate the impact of exercise on longevity?

Simulation

Experiment

Survey

Observational

Question 7(CO 1) What type of data collection might be best to study how voters might decide an upcoming ballot issue?

Simulation

Survey

Observational

Experiment

Question 8CO 1) You need to study the satisfaction of customers of a specific restaurant. You decide to randomly select one customer at each table. This would most closely describe which type of sampling technique?

Stratified

Random

Cluster

Systematic

Question 9(CO 1) Which of the following graphs would be a Pareto chart?

Vertical bars with spaces between with highest to left and shortest to right

Horizontal bars with various lengths

Vertical base with spaces between of various heights

Vertical bars with various lengths

Question 10(CO 1) In a normally distributed data set of how long customers stay in your store, the mean is 31.7 minutes and the standard deviation is 1.9minutes . Within what range would you expect 95% of your customers to stay in your store?

27.9-35.5

30.75-32.7

29.8-33.6

26.0-37.4

MATH221 Statistics for Decision Making

Week 5 Quiz

Question 1(CO 3) Consider the following table:

Age Group Frequency

18-29 983

30-39 784

40-49 686

50-59 632

60-69 541

70 and over 527

If you created the probability distribution for these data, what would be the probability of 30-39?

0.165

0.237

0.425

0.189

Question 2(CO 3) Consider the following table of hours worked by part-time employees. These employees must work in 5 hour blocks.

Weekly hours worked Probability

5 0.06

15 0.61

20 0.18

25 0.15

Find the mean of this variable.

12.20

17.50

18.95

16.80

Question 3(CO 3) Consider the following table.

Defects in batch Probability

0 0.30

1 0.28

2 0.21

3 0.09

4 0.08

5 0.04

Find the variance of this variable.

1.49

0.67

1.41

1.99

Question 4(CO 3) Consider the following table:

Defects in batch Probability

0 0.21

1 0.28

2 0.30

3 0.09

4 0.08

5 0.04

Find the standard deviation of this variable.

1.33

1.67

1.78

1.41

Question 5(CO 3) Twenty-two percent of US teens have heard of a fax machine. You randomly select 12 US teens. Find the probability that the number of these selected teens that have heard of a fax machine is exactly six (first answer listed below). Find the probability that the number is more than 8 (second answer listed below).

0.024, 0.001

0.993, 0.000

0.993, 0.024

0.024, 0.000

Question 6(CO 3) Ten rugby balls are randomly selected from the production line to see if their shape is correct. Over time, the company has found that 85.2% of all their rugby balls have the correct shape. If exactly 7 of the 10 have the right shape, should the company stop the production line?

Yes, as the probability of seven having the correct shape is not unusual

Yes, as the probability of seven having the correct shape is unusual

No, as the probability of seven having the correct shape is not unusual

No, as the probability of seven having the correct shape is unusual

Question 7(CO 3) A bottle of water is supposed to have 12 ounces. The bottling company has determined that 98% of bottles have the correct amount. Which of the following describes a binomial experiment that would determine the probability that a case of 36 bottles has all bottles properly filled?

n=12, p=36, x=98

n=36, p=0.98, x=36

n=36, p=0.98, x=12

n=0, p=0.98, x=36

Question 8(CO 3) On the production line the company finds that 95.6% of products are made correctly. You are responsible for quality control and take batches of 30 products from the line and test them. What number of the 30 being incorrectly made would cause you to shut down production?

Less than 26

Less than 28

Less than 27

More than 25

Question 9(CO 3) The probability of someone ordering the daily special is 52%. If the restaurant expected 65 people for lunch, how many would you expect to order the daily special?

34

35

30

31

Question 10(CO 3) Fifty-seven percent of employees make judgements about their co-workers based on the cleanliness of their desk. You randomly select 8 employees and ask them if they judge co-workers based on this criterion. The random variable is the number of employees who judge their co-workers by cleanliness. Which outcomes of this binomial distribution would be considered unusual?

0, 1, 8

1, 2, 8

1, 2, 8

0, 1, 2, 8

MATH221 Statistics for Decision Making

Week 7 Quiz

Question 1(CO 4) From a random sample of 55 businesses, it is found that the mean time that employees spend on personal issues each week is 4.9 hours with a standard deviation of 0.35 hours. What is the 95% confidence interval for the amount of time spent on personal issues?

(4.81, 4.99)

(4.84, 4.96)

(4.83, 4.97)

(4.82, 4.98)

Question 2(CO 4)If a confidence interval is given from 8.50 to 10.25 and the mean is known to be 9.375, what is the margin of error?

1.750

0.875

8.500

0.438

Question 3(CO 4) If the population standard deviation of a increases without other changes, what is most likely to happen to the confidence interval?

does not change

widens

cannot determine

narrows

Question 4(CO 4) From a random sample of 41 teens, it is found that on average they spend 43.1 hours each week online with a population standard deviation of 5.91 hours. What is the 90% confidence interval for the amount of time they spend online each week?

(37.19, 49.01)

(40.58, 45.62)

(31.28, 54.92)

(41.58, 44.62)

Question 5(CO 4) A company making refrigerators strives for the internal temperature to have a mean of 37.5 degrees with a population standard deviation of 0.6 degrees, based on samples of 100. A sample of 100 refrigerators have an average temperature of 37.48 degrees. Are the refrigerators within the 90% confidence interval?

Yes, the temperature is within the confidence interval of (37.40, 37.60)

Yes, the temperature is within the confidence interval of (36.90, 38.10)

No, the temperature is outside the confidence interval of (36.90, 38.10)

No, the temperature is outside the confidence interval of (37.40, 37.60)

Question 6(CO 4) What is the 97% confidence interval for a sample of 104 soda cans that have a mean amount of 15.10 ounces and a population standard deviation of 0.08 ounces?

(15.940, 15.260)

(15.083, 15.117)

(12.033, 12.067)

(15.020, 15.180)

Question 7(CO 4) Determine the minimum sample size required when you want to be 98% confident that the sample mean is within two units of the population mean. Assume a population standard deviation of 5.75 in a normally distributed population.

45

23

43

44

Question 8(CO 4) Determine the minimum sample size required when you want to be 80% confident that the sample mean is within 1.5 units of the population mean. Assume a population standard deviation of 9.24 in a normally distributed population.

62

146

145

63

Question 9(CO 4) Determine the minimum sample size required when you want to be 75% confident that the sample mean is within thirty units of the population mean. Assume a population standard deviation of 327.8 in a normally distributed population

158

324

197

157

Question 10(CO 4) In a sample of 8 high school students, they spent an average of 28.8 hours each week doing sports with a sample standard deviation of 3.2 hours. Find the 95% confidence interval, assuming the times are normally distributed.

(25.62, 32.48)

(24.10, 34.50)

(26.12, 31.48)

(22.47, 35.21)