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April 17, 2014

Homework Help: Math 126

Posted by Anonymous on Monday, July 16, 2012 at 12:00am.

These are the automatically computed results of your exam. Grades for essay questions, and comments from your instructor, are in the "Details" section below. Date Taken: 7/15/2012
Time Spent: h , min , 19 secs
Points Received: 18 / 20 (90%)

Question Type: # Of Questions: # Correct:
Multiple Choice 20 18


Grade Details - All Questions
1. Question : Armia's percentile rank on an exam in a class of 300 is 85. Sanjo's class rank is 42. Who is ranked higher?


Student Answer: Armia
Sanjo
Instructor Explanation: See section 12.5 of the textbook.


Points Received: 1 of 1
Comments:



2. Question : Find the area under the normal distribution curve to the right of z = 1.03.


Student Answer: 0.151
0.349
0.349
0.849
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 0 of 1
Comments: correct answer is 0.849



3. Question : Find the area under the normal distribution curve between z = 1.34 and z = 2.95.


Student Answer: 0.908
0.088
0.410
0.498
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 1 of 1
Comments:



4. Question : Find the median and the mean for the data set below.
5.4 2.0 6.8 3.1 2.9 4.7 2.1 5.0 1.9 3.4


Student Answer: mean = 37.3; median = 3.25
mean = 3.73; median = 3.4
mean =37.3; median = 3.4
mean = 3.73; median = 3.25
Instructor Explanation: See section 12.3 of the textbook.


Points Received: 1 of 1
Comments:



5. Question : Determine whether a correlation coefficient of r = 0.405 is significant at the 5% level for a sample size of 22.


Student Answer: r is not significant at 5%.
r is significant at 5%.
Instructor Explanation: See section 12.8 of the textbook.


Points Received: 1 of 1
Comments:



6. Question : Kate scored in the 95th percentile rank on an exam. If 400 students took the exam, how many students scored lower than Kate?


Student Answer: 379
381
378
380
Instructor Explanation: See section 12.5 of the textbook.


Points Received: 1 of 1
Comments:



7. Question : Which statement is true for a statistical study?


Student Answer: The sample is a subset of the population.
The population is a subset of the sample.
Instructor Explanation: See section 12.1 of the textbook.


Points Received: 1 of 1
Comments:



8. Question : Fran's percentile rank on an exam in a class of 500 is 85. Kelly's class rank is 60. Who is ranked higher?


Student Answer: Kelly
Fran
Instructor Explanation: See section 12.5 of the textbook.


Points Received: 1 of 1
Comments:



9. Question : The average hourly wage of employees of a certain company is $9.83. Assume the variable is normally distributed. If the standard deviation is $4.58, find the probability that a randomly selected employee earns less than $5.43.


Student Answer: 0.313 = 31.3%
0.332 = 33.2%
0.168 = 16.8%
0.345 = 34.5%
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 0 of 1
Comments: Correct answer is 16.8



10. Question : The area under a normal distribution curve that lies within one standard deviation of the mean is approximately _____.


Student Answer: 95%
99.7%
68%
65%
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 1 of 1
Comments:



11. Question : Find the area under the normal distribution curve between z = 1.52 and z = 2.43.


Student Answer: 0.929
0.436
0.493
0.057
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 1 of 1
Comments:



12. Question : The average amount customers at a certain grocery store spend yearly is $636.55. Assume the variable is normally distributed. If the standard deviation is $89.46, find the probability that a randomly selected customer spends between $550.67 and $836.94.


Student Answer: 0.144 = 14.4%
0.820 = 82.0%
0.156 = 15.6%
0.943 = 94.3%
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 1 of 1
Comments:



13. Question : For the 20 test scores shown, find the percentile rank for a score of 86.
75 63 92 74 86 50 77 82 98 65 71 89 75 66 87 59 70 83 91 73


Student Answer: 75th percentile
30th percentile
80th percentile
70th percentile
Instructor Explanation: See section 12.5 of the textbook.


Points Received: 1 of 1
Comments:



14. Question : Find the median.
2 27 38 55 49 9 53 34


Student Answer: 38
36
49
52
Instructor Explanation: See section 12.3 of the textbook.


Points Received: 1 of 1
Comments:



15. Question : Use a scatter plot to deternine the relationship between the x values and the y values.



Student Answer: No relationship
Nonlinear relationship
Positive linear relationship
Negative linear relationship
Instructor Explanation: See section 12.8 of the textbook.


Points Received: 1 of 1
Comments:



16. Question : Which of the following is not a property of a normal distribution?


Student Answer: It never touches the x-axis.
It is continuous.
The mean, median, and mode are equal.
It is bimodal (i.e., it has two modes).
Instructor Explanation: See section 12.6 of the textbook.


Points Received: 1 of 1
Comments:



17. Question : To select a _________ sample, the population is divided into disjoint subgroups according to some characteristics like income level, and then a few individuals are selected randomly from each of the subgroups to be in the sample.


Student Answer: stratified
random
cluster
systematic
Instructor Explanation: See section 12.1 of the textbook.


Points Received: 1 of 1
Comments:



18. Question : Find the value for the correlation coefficient r.



Student Answer: 0.073
0.094
0.203
0.149
Instructor Explanation: See section 12.8 of the textbook.


Points Received: 1 of 1
Comments:



19. Question : A data set of size 19 has correlation coefficient of r = 0.432. Test the significance of r at the 5% level and at the 1% level.


Student Answer: r is significant at 5% and at 1%.
r is significant at 5%, but not at 1%.
r is is not significant at 5% or at 1%.
Instructor Explanation: See section 12.8 of the textbook.


Points Received: 1 of 1
Comments:



20. Question : If a student's percentile rank in a class of 400 students is 87, find the student's class rank.


Student Answer: 40
44
48
52
Instructor Explanation: See section 12.5 of the textbook.


Points Received: 1 of 1
Comments:

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