# Math 126

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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

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?

Sanjo
Instructor Explanation: See section 12.5 of the textbook.

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

–0.349
0.349
0.849
Instructor Explanation: See section 12.6 of the textbook.

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

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

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.

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.

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?

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

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.

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?

Fran
Instructor Explanation: See section 12.5 of the textbook.

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.

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

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

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

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

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

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.

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

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

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

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

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

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

Nonlinear relationship
Positive linear relationship
Negative linear relationship
Instructor Explanation: See section 12.8 of the textbook.

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.

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.

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

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

–0.094
–0.203
–0.149
Instructor Explanation: See section 12.8 of the textbook.

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.

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

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

• Math 126 - ,

• Math 126 - ,

ALL OF THESE ARE WRONG I DOUBLE CHECKED AND IT SCORED A 8/20 THANKS A LOT smh

• Math 126 - ,

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.

• Math 126 - ,

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

• Math 126 - ,

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!

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