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:
The answer is 52
ALL OF THESE ARE WRONG I DOUBLE CHECKED AND IT SCORED A 8/20 THANKS A LOT smh
I'm sorry luckily I did not use your answers for my exam, but you should know these answers are ALL wrong! You have a few correct ones, but most are NOT correct.
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
I changed my answer to match yours and yours were all wrong, mine were right, thanks for posting false information!!! I only wanted to double check my work!!! Wish I would have seen these comments before!
To answer these questions, you can consult the textbook mentioned in the comments section for each question. Each question refers to a specific section of the textbook where you can find the necessary information to solve it. It is recommended to read those sections of the textbook thoroughly to understand the concepts and formulas required to answer the questions correctly.
For example, for question 1, you need to refer to section 12.5 of the textbook. You can find the answer by understanding percentiles and comparing Armia's percentile rank and Sanjo's class rank.
Similarly, for question 2, you need to refer to section 12.6 of the textbook to understand how to find the area under the normal distribution curve given a specific z-score.
Make sure to carefully read the instructor explanations provided in the comments section for each question, as they can provide additional guidance on how to approach the problem and where to find the relevant information in the textbook.
Overall, a thorough understanding of the relevant sections in the textbook and careful reading of the instructions and explanations provided will help you accurately answer the questions.