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:
5 answers
1 answer