Math
posted by Latisha .
Can someone please help me with these three question? I having a very difficlut time answering them
May first 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. (Points : 1)
(May choices are)
stratified
random
cluster
systematic
May second question
If a student's percentile rank in a class of 400 students is 87, find the student's class rank. (Points : 1)
(My choices are)
40
44
48
52
My final 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?
(My choices are)
Armia
Sanjo
Thanks you

automatically computed results of your exam. Grades for essay questions, and comments from your instructor, are in the "Details" section below. Date Taken: 3/3/2011
Time Spent: 1 h , 01 min , 31 secs
Points Received: 16 / 20 (80%)
Question Type: # Of Questions: # Correct:
Multiple Choice 20 16
Grade Details
1. 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:
2. Question : Which of the following is not a property of a normal distribution?
Student Answer: It never touches the xaxis.
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:
3. Question : If a student's rank in a class of 400 students is 44, find the student's percentile rank.
Student Answer: 88
89
87
90
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 1 of 1
Comments:
4. 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:
5. 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:
6. Question : Find the area under the normal distribution curve to the right of z = –3.24.
Student Answer: 0.499
–0.499
0.999
0.001
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 1 of 1
Comments:
7. 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: 1 of 1
Comments:
8. 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: 0 of 1
Comments:
9. Question : Find the equation of the regression line.
Student Answer: y = 1.7 + 1.9x
y = 2.5 + 2.7x
y = 1.9 + 1.7x
y = 2.7 + 2.5x
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 1 of 1
Comments:
10. 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:
11. 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:
12. Question : Find Q1, Q2, and Q3 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: Q1 = 2.05, Q2 = 3.1, Q3 = 5.2
Q1 = 2.05, Q2 = 3.25, Q3 = 5.2
Q1 = 2.1, Q2 = 3.25, Q3 = 5.0
Q1 = 2.1, Q2 = 3.4, Q3 = 5.0
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 1 of 1
Comments:
13. Question : Find the standard deviation.
44 46 33 10 50 27
Student Answer: 1694
186.67
14.97
224.1
Instructor Explanation: See section 12.4 of the textbook.
Points Received: 1 of 1
Comments:
14. 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: 0 of 1
Comments:
15. 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:
16. 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: 0 of 1
Comments:
17. 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:
18. 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:
19. 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. 
these answers are incorrect, i chnaged my answers to reflect his and all the answers that he has were incorrect don't use this the person chnaged the score

1. 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:
2. 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:
3. 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:
4. 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:
5. Question : Find the equation of the regression line.
Student Answer: y = 1.7 + 1.9x
y = 2.5 + 2.7x
y = 1.9 + 1.7x
y = 2.7 + 2.5x
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 0 of 1
Comments:
6. Question : Find the standard deviation.
44 46 33 10 50 27
Student Answer: 1694
186.67
14.97
224.1
Instructor Explanation: See section 12.4 of the textbook.
Points Received: 1 of 1
Comments:
7. 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:
8. 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: 0 of 1
Comments:
9. 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: 0 of 1
Comments:
10. 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:
11. 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:
12. 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:
13. 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:
14. 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:
15. 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:
16. Question : Find the area under the normal distribution curve to the right of z = –3.24.
Student Answer: 0.499
–0.499
0.999
0.001
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 1 of 1
Comments:
17. 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: 1 of 1
Comments:
18. 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:
19. 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:
20. Question : Which of the following is not a property of a normal distribution?
Student Answer: It never touches the xaxis.
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: 
For some reason when posted the answers show differently. Here are all the answers, which are correct:
1.0.057
2. 68%
3.r is not significant at 5% or at 1%.
4.0.820 = 82.0%
5.y = 1.7 + 1.9x
6.14.97
7.Kelly
8.r is not significant at 5%.
9.Positive linear relationship
10.70th percentile
11.0.908
12.52
13.stratified
14.380
15.Sanjo
16.0.999
17.0.849
18.mean = 3.73; median = 3.25
19.The sample is a subset of the population.
20.It is bimodal (i.e., it has two modes). 
SO MUCH FOR THE HELP. IF YOU ARE GOING TO POST HERE MAE SURE YOUR ANSWERS ARE LEGIT ....NOT COOL ;/
1. Question :
Find the area under the normal distribution curve to the right of z = –3.24.
Student Answer: INCORRECT 0.499
–0.499
CORRECT 0.999
0.001
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 0 of 1
Comments:
Question 2. Question :
Find the standard deviation.
44 46 33 10 50 27
Student Answer: INCORRECT 1694
186.67
CORRECT 14.97
224.1
Instructor Explanation: See section 12.4 of the textbook.
Points Received: 0 of 1
Comments:
Question 3. Question :
Find the area under the normal distribution curve to the right of z = –1.03.
Student Answer: INCORRECT 0.151
–0.349
0.349
CORRECT 0.849
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 0 of 1
Comments:
Question 4. 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
CORRECT 52
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 1 of 1
Comments:
Question 5. 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
CORRECT 70th percentile
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 1 of 1
Comments:
Question 6. Question :
Find the value for the correlation coefficient r.
Student Answer: –0.073
CORRECT –0.094
–0.203
–0.149
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 1 of 1
Comments:
Question 7. Question :
Which of the following is not a property of a normal distribution?
Student Answer: INCORRECT It never touches the xaxis.
It is continuous.
The mean, median, and mode are equal.
CORRECT It is bimodal (i.e., it has two modes).
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 0 of 1
Comments:
Question 8. Question :
Which statement is true for a statistical study?
Student Answer: CORRECT 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:
Question 9. 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: INCORRECT r is significant at 5% and at 1%.
r is significant at 5%, but not at 1%.
CORRECT r is is not significant at 5% or at 1%.
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 0 of 1
Comments:
Question 10. Question :
Find the equation of the regression line.
Student Answer: CORRECT y = 1.7 + 1.9x
y = 2.5 + 2.7x
y = 1.9 + 1.7x
y = 2.7 + 2.5x
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 1 of 1
Comments:
Question 11. Question :
If a student's rank in a class of 400 students is 44, find the student's percentile rank.
Student Answer: INCORRECT 88
CORRECT 89
87
90
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 0 of 1
Comments:
Question 12. Question :
Use a scatter plot to deternine the relationship between the x values and the y values.
Student Answer: CORRECT Negative linear relationship
Nonlinear relationship
INCORRECT No relationship
Positive linear relationship
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 0 of 1
Comments:
Question 13. Question :
Determine whether a correlation coefficient of r = –0.405 is significant at the 5% level for a sample size of 22.
Student Answer: CORRECT r is not significant at 5%.
INCORRECT r is significant at 5%.
Instructor Explanation: See section 12.8 of the textbook.
Points Received: 0 of 1
Comments:
Question 14. 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: CORRECT stratified
random
cluster
systematic
Instructor Explanation: See section 12.1 of the textbook.
Points Received: 1 of 1
Comments:
Question 15. 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: INCORRECT mean = 37.3; median = 3.25
mean = 3.73; median = 3.4
mean =37.3; median = 3.4
CORRECT mean = 3.73; median = 3.25
Instructor Explanation: See section 12.3 of the textbook.
Points Received: 0 of 1
Comments:
Question 16. 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: INCORRECT 379
381
378
CORRECT 380
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 0 of 1
Comments:
Question 17. 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: CORRECT Kelly
Fran
Instructor Explanation: See section 12.5 of the textbook.
Points Received: 1 of 1
Comments:
Question 18. Question :
Find the area under the normal distribution curve between z = –1.34 and z = 2.95.
Student Answer: CORRECT 0.908
0.088
0.410
0.498
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 1 of 1
Comments:
Question 19. 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: INCORRECT 0.144 = 14.4%
CORRECT 0.820 = 82.0%
0.156 = 15.6%
0.943 = 94.3%
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 0 of 1
Comments:
Question 20. Question :
The area under a normal distribution curve that lies within one standard deviation of the mean is approximately _____.
Student Answer: INCORRECT 95%
99.7%
CORRECT 68%
65%
Instructor Explanation: See section 12.6 of the textbook.
Points Received: 0 of 1
Comments: