Hi
could i get help and references to the following
From the question I have worked out the population of subject marks as
follows:
a. 28.2 27.2 30.2 31.2 24.2
3.2 18.2 26.2 25.2 29.2
13.2 25.2 38.2 21.2 31.2
15.2 9.2 28.2 26.2 19.2
31.2 33.2 20.2 12.2 20.2
22.2 8.2 27.2 2.2 27.2
13.2 29.2 23.2 29.2 33.2
30.2 23.2 33.2 25.2 27.2
22.2 21.2 20.2 30.2 12.2
b. Calculate mean, mode, median and standard deviation of this
population of marks giving precise unit of measurement of each.
I have worked out as follows:
Mean = 23.267
Mode = 27.2
Median = 25.2
SD = 8.11415498
Is the above correct?
c. From the results obtained in b. show and argue whether the
distribution is normal, approximately normal or clearly non-normal.
Please explain in detail this question. I have looked around but was
not able to obtain satisfactory results.
d. Express numerical version of sample data given in ques(a)above with sample
size of 14.
my answer
30.2 31.2 24.2 3.2
18.2 26.2 25.2 29.2
13.2 25.2 38.2 21.2
31.2 15.2
e. Calculate sample mean, sample variance and sample SD giving
precise unit of measurement for each
Sample mean = 23.700
Sample variance = 80
Sample SD = 8.9442719099
Is all of ques e correct?
I NEED HELP FROM HERE ON
f. How do I calculate true mean of the population using 90%
confidence level
g. Explain what is meant by sampling distribution of the sample mean
and cast your explanation in a way that it assists in giving a clear
interpretation of the results provided in f.
h. Suppose the true mean is less than 29. Use the sample data to
test this hypothesis at the 10 percent significance level. Explain
the meaning of what is involved in such a test (null hypotheses,
alternative hypotheses, significance level, type I/type II error, test
statistic, sampling distribution of the test statistic, value of test
statistics, result being statistically significant/not statistically
significant.
i. Explain whether you are satisfied with the use of the sample size
n = 14. Explain why and how the quality of the statistical results
will change if a smaller ie: n = 45 sample is used.
I would really appreciate if I could get my answers for the above
question
thank you
Elshana |
Request for Question Clarification by
elmarto-ga
on
17 Sep 2003 17:30 PDT
Hi elshana!
I think I can answer yuor question, but I would need some
clarification first.
In question (f) you ask to calculate the true mean with 90%
confidence. What does this mean? If the population is the one
described in question (a), then the "true" mean is the population
mean, which was calculated in question (b). Maybe the question implies
"what if you only had the sample of 14 observations described in
question (d), and you didn't have the population". But in this case,
since "confidence level" is related to hypothesis testing, what is the
hypothesis you want to test in this question?
I have thus assumed for this question that:
a) You don't have the population.
b) You want to test the hypothesis that the population means is equal
to the observed sample mean (23.7) with a 90% confidence level.
Is this assumption correct?
Best regards,
elmarto
|
