Statistics Homework

Need to have someone who good at statistic…Also need homework back by 4/20/13 at 9pm eastern time.

Con

s

ider the following statement for questions 1-5

It is given that

50

.

132

$

=

s
for the expenses of books and supplies for the students of a certain large university for a semester. To estimate the mean of such expenses for all the students, a simple random sample of 35 students is taken and the mean for these 35 students is
63
.
397
$
=
x
.
1. What is the margin of error of your estimate of the population mean at a 95% confidence level?
2. Construct a 95% confidence interval for the mean such expenses for all the students.
3. What is the margin of error of your estimate of the population mean at a 99% confidence level?
4. Construct a 99% confidence interval for the mean such expenses for all the students.
5. Which of the two confidence interval is wider?
Consider the following for the questions 6-9
We have to construct a confidence interval for the mean of SAT (verbal and quantitative) scores of students who use a special coaching. How large a sample must be taken to participate in the coaching group to estimate this mean with a margin of error of no more than 25 points if we can assume that the population standard deviation is 175 points for the reference population?
Compute the required sample size for each of the following confidence levels.
6. 90% confidence
7. 95% confidence
8. 99% confidence
Consider the following for the questions 10-12
A clinic claims that the average time taken by a patient to see the doctor from the appointment time
is 30 minutes. A simple random sample of 35 patients is contacted the mean of the wait time for this sample is 47 minutes and the standard deviation of the wait time for this sample is 12 minutes.
10. What is the margin of error of your estimate of the population mean at a 95% confidence level?
11. Construct a 95% confidence interval for the mean wait time for all the patients.
12. Is 30 minute in this interval?
Consider the following for the questions 13-15
In a simple random sample of 821 citizens, 63% said that they approve the tax raise for improving the infra-structure of the nation.
13. What is the margin of error of your estimate of the population proportion at a 95% confidence level?
14. Construct a 95% confidence interval for the proportion of all the people who approve the tax raise for improving the infra-structure of the nation.
15. How large a sample should be taken to estimate this proportion with 95% confidence with a margin of error of no more than 2% points.

Atul N Roy
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