Devry MATH221 All Homeworks Latest 2021 June

MATH221 Statistics for Decision Making

Week 1 Homework

Question 1In a survey of 1000 adults, 34% found they prefer charcoal to gas grills. The 34% would be considered a:

  Statistic

  Population

  Parameter

  Sample

 Question 2The chances of winning the Maryland lottery are one chance in twenty-two million. The probability would be considered an example of:

  Inferential statistics

  Experiment design

  Descriptive statistics

  A sample

Question 3 The milligrams of tar in 30 cigarettes would be considered:

  Ordinal data

  Nominal data

  Interval data

  Ratio data

Question 4The ratings of 50 movies would be considered:

  Ordinal data

  Interval data

  Ratio data

  Quantitative data

Question 5A researcher randomly selects and interviews fifty male and fifty female teachers. This sampling technique is called:

  Cluster

  Random

  Convenience

  Stratified

 

 

MATH221 Statistics for Decision Making

Week 2 Homework

Question 1 Given the following information, find the probability that a randomly selected student will be very short. Number of students who are very short: 45, short: 60, tall: 82, very tall: 21

  28.8%

  21.6%

  21.0%

  39.4%

 Question 2Given the following information, find the probability that a randomly selected dog will be a poodle. Number of dogs who are poodles: 31, golden retrievers: 58, beagles: 20, pugs: 38

  58.0%

  42.0%

  39.5%

  21.1%

Question 3Given that there is a 21% chance it will rain on any day, what is the probability that it will rain on the first day and be clear (not rain) on the next two days?

  13.1%

  36.2%

  16.6%

  21.0%

Question 4Consider the following table. What is the probability of no?

                Red        Blue       Total

Yes         15           21           36

No          38           13           51

Total      53           34           87

  13/51

  51/34

  13/34

  51/87

 Question 5Consider the following table. What is probability of yes, given green?

 

                Red        Blue       Green   Total

Yes         33           44           14           91

No          18           5              28           51

Total      51           49           42           142

  51/142

  14/42

  42/142

  14/91

 

MATH221 Statistics for Decision Making

Week 3 Homework

Question 1Let x represent the height of first graders in a class. This would be considered what type of variable:

  Nonsensical

  Lagging

  Discrete

  Continuous

 Question 2Let x represent sheets of paper in a package. This would be considered what type of variable:

 Discrete

  Continuous

  Distributed

  Inferential

 Question 3Consider the following table.

Age Group          Frequency

18-29     9831

30-39     7845

40-49     6869

50-59     6323

60-69     5410

70 and over        5279

If you created the probability distribution for these data, what would be the probability of 60-69?

  13.0%

  12.7%

  15.2%

  18.9%

 Question 4Consider the following table.

Weekly hours worked   Probability

1-30 (average=22)           0.08

31-40 (average=35)         0.16

41-50 (average=46)         0.72

51 and over (average=61)            0.04

 Find the mean of this variable.

  44.2

  49.2

  42.9

  41.0

 Question 5Consider the following table.

Defects in batch               Probability

0              0.28

1              0.35

2              0.16

3              0.09

4              0.10

5              0.02

 Find the variance of this variable.

  1.83

  1.35

  0.85

  1.44

 

 

MATH221 Statistics for Decision Making

Week 4 Homework

Question 1The length of time a person takes to decide which shoes to purchase is normally distributed with a mean of 8.54 minutes and a standard deviation of 1.91. Find the probability that a randomly selected individual will take less than 6 minutes to select a shoe purchase. Is this outcome unusual?

  Probability is 0.09, which is unusual as it is less than 5%

  Probability is 0.09, which is usual as it is not less than 5%

  Probability is 0.91, which is unusual as it is greater than 5%

  Probability is 0.91, which is usual as it is greater than 5%

 Question 2In a health club, research shows that on average, patrons spend an average of 42.5 minutes on the treadmill, with a standard deviation of 4.8 minutes. It is assumed that this is a normally distributed variable. Find the probability that randomly selected individual would spent between 30 and 40 minutes on the treadmill.

  Less than 1%

  0.70

  0.30

  0.40

 Question 3A tire company measures the tread on newly-produced tires and finds that they are normally distributed with a mean depth of 0.98mm and a standard deviation of 0.35mm. Find the probability that a randomly selected tire will have a depth less than 0.50mm. Would this outcome warrant a refund (meaning that it would be unusual)?

  Probability of 0.91 and would warrant a refund

  Probability of 0.91 and would not warrant a refund

  Probability of 0.09 and would not warrant a refund

  Probability of 0.09 and would warrant a refund

 Question 4In an agricultural study, the average amount of corn yield is normally distributed with a mean of 189.3 bushels of corn per acre, with a standard deviation of 23.5 bushels of corn. If a study included 1200 acres, about how many would be expected to yield more than 180 bushels of corn per acre?

  785 acres

  654 acres

  346 acres

  415 acres

 Question 5On average, the parts from a supplier have a mean of 31.8 inches and a standard deviation of 2.4 inches. Find the probability that a randomly selected part from this supplier will have a value between 27.0 and 36.6 inches. Is this consistent with the Empirical Rule of 68%-95%-99.7%?

 Probability is 0.95, which is consistent with the Empirical Rule

  Probability is 0.02, which is inconsistent with the Empirical Rule

  Probability is 0.98, which is inconsistent with the Empirical Rule

  Probability is 0.95, which is inconsistent with the Empirical Rule

 

MATH221 Statistics for Decision Making

Week 5 Homework

Question 1From a random sample of 58 businesses, it is found that the mean time the owner spends on administrative issues each week is 20.53 with a population standard deviation of 3.54. What is the 95% confidence interval for the amount of time spent on administrative issues?

  (16.99, 24.07)

  (19.62, 21.44)

  (19.24, 24.14)

  (13.45, 27.61)

 Question 2If a confidence interval is given from 45.82 up to 55.90 and the mean is known to be 50.86, what is the margin of error?

  10.08

  2.52

  45.82

  5.04

 Question 3If a car manufacturer wanted lug nuts that fit nearly all the time, what characteristics would be better?

  wide confidence interval with low confidence level

  narrow confidence interval at high confidence level

  wide confidence interval with high confidence level

  narrow confidence interval at low confidence level

 Question 4The 95% confidence interval for these parts is 56.98 to 57.05 under normal operations. A systematic sample is taken from the manufacturing line to determine if the production process is still within acceptable levels. The mean of the sample is 57.04. What should be done about the production line?

  Stop the line as it is inside the confidence interval

  Stop the line as it is outside the confidence interval

  Keep the line operating as it is outside the confidence interval

  Keep the line operating as it is inside the confidence interval

 Question 5In a sample of 41 temperature readings taken from the freezer of a restaurant, the mean is 29.7 degrees and the population standard deviation is 2.7 degrees. What would be the 80% confidence interval for the temperatures in the freezer?

  (31.36, 32.44)

  (24.30, 35.10)

  (29.16, 30.24)

  (27.00, 32.4)

 

MATH221 Statistics for Decision Making

Week 6 Homework

Question 1A consumer analyst reports that the mean life of a certain type of alkaline battery is no more than 63 months. Write the null and alternative hypotheses and note which is the claim.

  Ho: μ = 63 (claim), Ha: μ ≥ 63

  Ho: μ ≤ 63 (claim), Ha: μ > 63

  Ho: μ ≤ 63, Ha: μ > 63 (claim)

  Ho: μ > 63 (claim), Ha: μ ≤ 63

 Question 2An amusement park claims that the average daily attendance is at least 15,000. Write the null and alternative hypotheses and note which is the claim.

 Ho: μ ≥ 15000 (claim), Ha: μ < 15000

  Ho: μ = 15000, Ha: μ ≤ 15000 (claim)

  Ho: μ > 15000 (claim), Ha: μ = 15000

  Ho: μ ≤ 15000, Ha: μ > 15000 (claim)

 Question 3If the null hypothesis is rejected when it is true, this is called __________.

 >a type I error

  the Empirical Rule

  a type II error

  an alternative hypothesis

 Question 4A scientist claims that the mean gestation period for a fox is less than 50.3 weeks. If a hypothesis test is performed that rejects the null hypothesis, how would this decision be interpreted?

  There is enough evidence to support the scientist’s claim that the gestation period is less than 50.3 weeks

  There is not enough evidence to support the scientist’s claim that the gestation period is 50.3 weeks

  The evidence indicates that the gestation period is more than 50.3 weeks

  There is not enough evidence to support the scientist’s claim that the gestation period is more than 50.3 weeks

 Question 5A marketing organization claims that 10% of its employees are paid minimum wage. If a hypothesis test is performed that fails to reject the null hypothesis, how would this decision be interpreted?

  There is sufficient evidence to support the claim that 10% of the employees are paid minimum wage

  There is not sufficient evidence to support the claim that less than 10% of the employees are paid minimum wage

  There is not sufficient evidence to support the claim that 10% of the employees are paid minimum wage

  There is sufficient evidence to support the claim that more than 10% of the employees are paid minimum wage

 

MATH221 Statistics for Decision Making

Week 7 Homework

Question 1Two variables have a positive linear correlation. Does the dependent variable increase or decrease as the independent variable increases?

  Cannot determine from information given

  Dependent variable would remain the same

  Dependent variable increases

  Dependent variable decreases

 Question 2What does the variable r represent?

  The critical value for the correlation coefficient

  The sample correlation coefficient

  The coefficient of determination

  The population correlation coefficient

 Question 3A golfer wants to determine if the type of driver she uses each year can be used to predict the amount of improvement in her game. Which variable would be the response variable?

  The improvement in her game

  The type of driver

  The rating of the golfer

  The number of holes she plays

 Question 4What would be the notation for an estimate of y for a specific value of x?

  yi

  y?

  ?

  b

 Question 5Which of the following graphs displays the regression equation ?=-0.91x + 11.97

 Scatter plot generally from upper left to lower right where y-intercept is estimated to be around 12

  Scatter plot generally from upper left to lower right where y-intercept is estimated to be around 7

  Scatter plot generally from lower left to upper right where y-intercept is estimated to be around 30

  Scatter plot generally from lower left to upper right where y-intercept is estimated to be around 6