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Final Exam with Solutions - Statistical Methods | STAT 2000, Exams of Data Analysis & Statistical Methods

Utah State University (USU)Data Analysis & Statistical Methods

Material Type: Exam; Class: Statistical Methods; Subject: Statistics; University: Utah State University; Term: Spring 2000;

Typology: Exams

Pre 2010

Uploaded on 07/30/2009

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Stat 2000 International – Final - Answers
1. Correct answer: [3] the use of self-selected volunteers
2. Correct answer: [4] only the students who participated in the study
3. Correct answer: [4] diet plan
4. Correct answer: [3] The sample statistics would change if a new random sample were drawn.
5. Correct answer: [1] Average is larger
6. Correct answer: [3] Plot C
7. Correct answer: [4] Green = 3/4, Yellow = 1/4
8. Correct answer: [2] 0.0314
9. Correct answer: [3] 0.3
10. Correct answer: [2] 0.866
11. Correct answer: [2] about 0.049
12. Correct answer: [3] The sample means are spread from about 26 inches to about 32 inches.
13. Correct answer: [3] $0.28
14. Correct answer: [2] about 0.8414
15. Correct answer: [3] The manager can be 90% confident that the true average travel time
between customers is between 21.73 and 22.81 minutes.
16. Correct answer: [3] Ha: p > 1/2
17. Correct answer: [2] about 0.1667
18. Correct answer: [5] H0: Population mean = 400; Ha: Population mean =/= 400
19. Correct answer: [2] A t-test is a significance testing procedure used to evaluate hypothesis
statements about means.
20. Correct answer: [3] If the population mean is really 23, the probability is 0.0003 that the mean
of the 36 ages could be less than 23.
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Download Final Exam with Solutions - Statistical Methods | STAT 2000 and more Exams Data Analysis & Statistical Methods in PDF only on Docsity!

Stat 2000 International – Final - Answers

  1. Correct answer: [3] the use of self-selected volunteers
    1. Correct answer: [4] only the students who participated in the study
    2. Correct answer: [4] diet plan
    3. Correct answer: [3] The sample statistics would change if a new random sample were drawn.
    4. Correct answer: [1] Average is larger
    5. Correct answer: [3] Plot C
    6. Correct answer: [4] Green = 3/4, Yellow = 1/
    7. Correct answer: [2] 0.
    8. Correct answer: [3] 0.
  2. Correct answer: [2] 0.
  3. Correct answer: [2] about 0.
  4. Correct answer: [3] The sample means are spread from about 26 inches to about 32 inches.
  5. Correct answer: [3] $0.
  6. Correct answer: [2] about 0.
  7. Correct answer: [3] The manager can be 90% confident that the true average travel time between customers is between 21.73 and 22.81 minutes.
  8. Correct answer: [3] Ha: p > 1/
  9. Correct answer: [2] about 0.
  10. Correct answer: [5] H0: Population mean = 400; Ha: Population mean =/= 400
  11. Correct answer: [2] A t-test is a significance testing procedure used to evaluate hypothesis statements about means.
  12. Correct answer: [3] If the population mean is really 23, the probability is 0.0003 that the mean of the 36 ages could be less than 23.
  1. Correct answer: [1] Sample No. 1
  2. Correct answer: [4] There's not enough evidence to say the means are different.
  3. Correct answer: [2] Two possibilities are occupation and seniority.
  4. Correct answer: [4] 10 pounds
  5. Correct answer: [2] 850
  6. Answer: We need to know more about possible confounding factors. In particular, we need to know whether the only difference between the two groups is that one group smokes and the other group does not smoke. Do both groups exercise similarly? Do both groups eat healthily? Do both groups have the same genetic predisposition to heart disease?
  7. Answer: (a) Median height about 74 inches. (b) Tallest person about 84 inches. (c) About 75% above 72 inches.
  8. Answer: 2. This is linear with an outlier. (The points are exactly on a straight line, except for one.)
  9. Answer: Test results are independent so we use the special case rule for AND: P(test husband positive and test wife positive) = (0.85) * (0.85) = 0.
  10. Answer: You can start with the "Graphing Normal z-Score/Probability" calculator for example.

Enter 65 for the mean and 2.7 for the standard deviation. Calculate the "Area left of" 62 (0.1333) and "Area right of" 70 (0.032) and then subtract these two numbers from 1.0. This will tell us that the proportion of women between 62 and 70 inches tall is 1.0 - (0.1333 + 0.032) = 0.8347.

  1. Answer: You can start with the "Graphing Normal z-Score/Probability" calculator for example.

Enter 65 for the mean and 2.7 for the standard deviation. Choose "Area left of" and type in the area (the red number) as 0.60. Then click on "Compute!" and the answer will be that 65.68 is the 60th percentile.

  1. Answer: No! Generally, surveys of this type performed on the web do not involve obtaining a

random sample from the general population. Those who visit the web site and choose to respond are likely to differ from the general population. Therefore, the sample results should not be used to estimate the true percentage of Americans who believe in life "out there."

  1. Answer: The null hypothesis is that there is no relationship: H0: Population correlation

coefficient = 0. Because we are interested in negative correlation, the alternative hypothesis is Ha: Population correlation coefficient < 0.

  1. Answer: Mean blood pressure in the population of women is 115. The p-value is large (larger than 0.05) so we cannot reject the null hypothesis.
  1. Answer: HeartRate = -166.27835 + 2.4431736 * Temperature The p-value associated with Temperature is 0.0036 < 0.05, i.e., the slope is significantly different from 0. Therefore, we can use the regression equation to predict HeartRate from Temperature.
  2. Answer: Both histograms look somewhat similar, with a range from about 55 to about 90. Both

shapes look somewhat similar to the normal curve, although not perfect. Both could be slightly skewed towards the lower values. For Gender = 1, the mode is in the 70-75 class and for Gender = 2, the mode is in the 75-80 class.

  1. Answer:

Gender 1: HeartRate = -87.96204 + 1.6444824 * Temperature Gender 2: HeartRate = -233.61661 + 3.1279447 * Temperature

  1. Answer: For Gender 1, the p-value associated with Temperature is 0.1184 > 0.05, i.e., the slope is not significantly different from 0. For Gender 2, the p-value associated with Temperature is

0.0205 < 0.05, i.e., the slope is significantly different from 0. Therefore, we can use the regression equation only for Gender 2 to predict HeartRate from Temperature.

  1. Answer: For 97: around 69.79; for 99: around 76.05; for 104: around 91.69. The last value (for 104 degrees Fahrenheit = 40 degrees Celsius) is least reliable since 104 degrees is more than 3

degrees above the highest observed Temperature. We are extremely extrapolating here. This person may have a very critical medical condition and it may be very difficult to correctly predict the HeartRate.