MATH 221 STATISTICS FOR DECISION MAKING WEEK 3 HOMEWORK / 2020
DeVry MATH 221 Week 3 Homework Answers (2020)
1. Let x represent the height of first graders in a class. This would be considered what type of variable:
2. Let x represent the number of players on a sports field. This would be considered what type of variable:
3. Consider 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
|
4. Consider the following table.
Weekly hours worked
|
Probability
|
1-30 (average=22)
|
0.08
|
31-40 (average=35)
|
0.41
|
41-50 (average=46)
|
0.47
|
51 and over (average=61)
|
0.04
|
5. Consider the following table.
Defects in batch
|
Probability
|
0
|
0.05
|
1
|
0.18
|
2
|
0.29
|
3
|
0.24
|
4
|
0.13
|
5
|
0.11
|
6. Consider the following table.
Defects in batch
|
Probability
|
2
|
0.15
|
3
|
0.44
|
4
|
0.18
|
5
|
0.10
|
6
|
0.07
|
7
|
0.06
|
7. The standard deviation of samples from supplier A is 0.0841, while the standard deviation of samples from supplier B is 0.0926. Which supplier would you be likely to choose based on these data and why?
8. Ten fourth graders are randomly selected. The random variable represents the number of fourth graders who own a smartphone. For this to be a binomial experiment, what assumption needs to be made?
9. A survey found that 39% of all gamers play video games on their smartphones. Ten frequent gamers are randomly selected. The random variable represents the number of frequent games who play video games on their smartphones. What is the value of p?
10. Thirty-five percent of US adults have little confidence in their cars. You randomly select ten US adults. Find the probability that the number of US adults who have little confidence in their cars is (1) exactly six and then find the probability that it is (2) more than 7.
11. Say a business wants to know if each salesperson is equally likely to make a sale. The company chooses 5 salespeople and gathers information on their sales experiences. What assumption must be made for this study’s probability results to be used in future binomial experiments?
12. Eleven baseballs are randomly selected from the production line to see if their stitching is straight. Over time, the company has found that 98.3% of all their baseballs have straight stitching. If exactly nine of the eleven have straight stitching, should the company stop the production line?
13. A soup company puts 20 ounces of soup in each can. The company has determined that 97% of cans have the correct amount. Which of the following describes a binomial experiment that would determine the probability that a case of 24 cans has all cans that are properly filled?
14. A supplier must create metal rods that are 16.4 inches long to fit into the next step of production. Can a binomial experiment be used to determine the probability that the rods are too long, too short, or about right?
15. In a box of 12 tape measures, there is one that does not work. Employees take tape measures as needed and returned after use. You are the 9th employee to take a tape measure. Is this a binomial experiment?
16. Forty-two percent of employees make judgements about their co-workers based on the cleanliness of their desk. You randomly select 7 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?
17. Ninety-one percent of products come off the line within product specifications. Your quality control department selects 15 products randomly from the line each hour. Looking at the binomial distribution, if fewer than how many are within specifications would require that the production line be shut down (unusual) and repaired?
18. The probability of a potential employee passing a drug test is 86%. If you selected 12 potential employees and gave them a drug test, how many would you expect to pass the test?
19. The probability of a potential employee passing a training course is 86%. If you selected 15 potential employees and gave them the training course, what is the probability that 11 or less will pass the test?
20. Off the production line, there is a 4.6% chance that a candle is defective. If the company selected 50 candles off the line, what is the standard deviation of the number of defective candles in the group?
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