MATH 221 Week 3 Quiz 2

MATH 221 Week 3 Quiz 2 | Devry University

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 40-49?  

·         0.189  

·         0.425    

·         0.165  

·         0.237

 

 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           0.18

20           0.61

25           0.15

Find the mean of this variable.  

·         0.61  

·         12.20  

·         18.95 

·         2.70

 

Question 3

 (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 variance of this variable.  

·         1.67    

·         1.78 

·         1.33  

·         1.99

 

 Question 4

 (CO 3) Consider the following table:

Defects in batch               Probability

0              0.21

1              0.19

2              0.30

3              0.15

4              0.11

5              0.04

Find the standard deviation of this variable.  

·         1.99  

·         1.88  

·         1.40

·         1.97

 

Question 5

 (CO 3) Fifty-four 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).  

·         0.217, 0.120  

·         0.217, 0.280  

·         0.284, 0.160  

·         0.284, 0.120

 

 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 20 ounces. The bottling company has determined that 96% 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=20, p=0.98, x=36  

·         n=36, p=0.96, x=36  

·         n=36, p=0.98, x=1  

·         n=0, p=36, x=98

 

 Question 8

 (CO 3) On the production line the company finds that 90.2% 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 24  

·         Less than 25

 

 Question 9

 (CO 3) The probability of someone ordering the daily special is 52%. If the restaurant expected 105 people for lunch, how many would you expect to order the daily special?  

·         51  

·         52    

·         55  

·         100

 

 Question 10

 (CO 3) Forty-seven percent of employees make judgments 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, 7, 8  

·         0, 1, 8  

·         1, 2, 8  

·         0, 1, 2, 8

 

Question 11

 (CO 3) Sixty-five percent of products come off the line ready to ship to distributors. Your quality control department selects 12 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?  

·         Fewer than 6  

·         Fewer than 5  

·         Fewer than 4  

·         Fewer than 10

 

 Question 12

 (CO 3) Out of each 100 products, 93 are ready for purchase by customers. If you selected 20 products, what would be the expected (mean) number that would be ready for purchase by customers? 

·         18  

·         93    

·         19  

·         20

 

 Question 13

 (CO 3) Sixty-seven percent of adults have looked at their credit score in the past six months. If you select 31 customers, what is the probability that at least 25 of them have looked at their score in the past six months?  

·         0.030    

·         0.073  

·         0.970  

·         0.043

 

 Question 14

 (CO 3) One out of every 92 tax returns that a tax auditor examines requires an audit. If 70 returns are selected at random, what is the probability that less than 5 will need an audit?  

·         0.9990  

·         0.9999  

·         0.0009  

·         0.0102

 

 Question 15

 (CO 3) Thirty-eight percent of consumers prefer to purchase electronics online. You randomly select 16 consumers. Find the probability that the number who prefer to purchase electronics online is at most 6.  

·         0.202    

·         0.593  

·         0.391  

·         0.380

 

 Question 16

 (CO 3) In the morning, about 25% of adults know what they will have for dinner.  If one morning,  you ask 22 adults if they know what they will have for dinner, what is the probability that more than 8 will say yes? 

·         0.162  

·         0.087  

·         0.075  

·         0.925

 

 Question 17

 (CO 3) Among teenagers, 73% prefer watching shows over the internet, rather than through cable.  If you asked 29 teenagers if they preferred watching shows over the internet, rather than through cable, how many would you expect to say yes?  

·         21  

·         15  

·         23  

·         29

 

Question 18

 (CO 3) Sixty-four percent of those that use drive through services believe that the employees are at least somewhat rude.  If you asked 87 people who use drive through services if they believe that the employees are at least somewhat rude, what is the probability that at most 60 say yes?  

·         0.860  

·         0.198  

·         0.057 

·         0.802