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- From Mathematics, Statistics
- Due on 03 May, 2015 03:28:00
- Asked On 30 Apr, 2015 07:27:31
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1** Improving the productivity of chickens**. Farmers have discovered that more domestic chickens peck at objects placed in their environment, the healthier and more productive the chickens seem to be. White string has been found to be a particularly attractive pecking stimulus. In one experiment,

Previous research has shown that ** μ=7.5** pecks if chickens are exposed to white string. Conduct a test (at

(a) (8 points) Formulate the null and the alternative hypothesis.

(b)(8 points) State and calculate the test statistics from the data.

(c) (8 points) Draw a conclusion.

2. A five-year-old census recorded that 20% of the families in a large community lived below the poverty level. To determine if this percentage has changed, a random sample of 400 families is studied and 70 are found to be living below the poverty level. Does this finding indicate that the current percentage of families earning incomes below the poverty level has changed from what it was five years ago? Test with α=0.05.

(a) (8 points) Formulate the null and the alternative hypothesis.

(b)(8 points) State and calculate the test statistics from the data.

(c) (8 points) Draw a conclusion.

(d) (8 points) Calculate the P-value.

3. A city health department wishes to determine if the mean bacteria count per unit volume of water at a lake beach is within the safety level of 200. A researcher collected 10 water samples of unit volume and found the bacteria counts to be

175, 190, 205, 193, 184, 207, 204, 193, 196, 180

Do the data strongly indicate that there is no cause for concern? Test with α=0.05.

(a) (8 points) Formulate the null and the alternative hypothesis.

(b)(8 points) State and calculate the test statistics from the data.

(c)(8 points) Draw a conclusion.

(d) (8 points) Calculate the P-value.

4. (12 points) A limnologist wishes to estimate the mean phosphate content per unit volume of the lake water. It is known from studies in previous years that the standard deviation has a fairly stable value of σ=4. How many water samples must the limnologist analyze to be 90% certain that the error of estimation does not exceed 0.8 milligrams?

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1.
Decide if the probability described is a subjective (personal) probability or a relative frequency probability: A quarter is flipped 2000 times and results in 500 heads. The 25% (500/2000) chance of heads is a
A) subjective probability.
B) relative frequency probability.
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2.
A statistics class has 4 teaching assistants (TAs): three female assistants (Lauren, Rona, and Leila) and one male assistant (Josh). Each TA teaches one discussion section. A student picks a discussion section. The two events W = {the TA is a woman} and J = {the TA is Josh} are
A) independent events.
B) disjoint (mutually exclusive) events.
C) each simple events.
D) None of the above.
Feedback: These events are mutually exclusive since ...

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STAT 200: Introduction to Statistics Final Examination, Spring 2015 OL4/US2 Page 1 of 6
STAT 200
OL4 / US2 Sections
Final Exam
Spring 2015
This is an open-book exam. You may refer to your text and other course
materials as you work on the exam, and you may use a calculator. You must
complete the exam individually. Neither collaboration nor consultation with
others is allowed.
Answer all 25 questions. Make sure your answers are as complete as possible.
Show all of your work and reasoning. In particular, when there are
calculations involved, you must show how you come up with your answers
with critical work and/or necessary tables. Answers that come straight from
programs or software packages will not be accepted. If you need to use
software (for example, Excel) and /or online or hand-held calculators to aid in
your calculation, please cite the sources and explain how you get the results.
Record your answers and work on the separate answer sheet provided.
This exam has 250 total points.
You must include the Honor Pledge on the title page of your submitted final
exam. Exams submitted without the Honor Pledge will not be accepted.
STAT 200: Introduction to Statistics Final Examination, Spring 2015 OL4/US2 Page 2 of 6
1. True or False. Justify for full credit. (25 pts)
(a) If the variance from a data set is zero, then all the observations in this data set must
be identical.
(b) P(AANDA ) 1, whereA is the complement of A. c c
(c) The mean is always equal to the median for a normal distribution.
(d) A 99% confidence interval is wider than a 95% confidence interval of the same
parameter.
(e) It is easier to reject the null hypothesis if we use a smaller significance level α.
Refer to the following frequency distribution for Questions 2, 3, 4, and 5. Show all work. Just the
answer, without supporting work, will receive no credit.
A random sample of 25 customers was chosen in UMUC MiniMart between 3:00 and 4:00
PM on a Friday afternoon. The frequency distribution below shows the distribution for
checkout time (in minutes).
Checkout Time (in minutes) Frequency Relative Frequency
1.0 - 1.9 4
2.0 - 2.9
0.4
3.0 - 3.9
4.0 - 4.9 5
Total 25
2. Complete the frequency table with frequency and relative frequency. (5 pts)
3. What percentage of the checkout times was at least 3 minutes? (5 pts)
4. In what class interval must the median lie? Explain your answer. (5 pts)
5. Assume that the largest observation in this dataset is 4.8. Suppose this observation were
incorrectly recorded as 8.4 instead of 4.8. Will the mean increase, decrease, or remain
the same? Will the median increase, decrease or remain the same? Why? (5 pts)
Refer...

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