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Did some body knows about statistics

Customer Question

Did some body knows about statistics?
Submitted: 9 years ago.
Category: Homework
Expert:  Manal Elkhoshkhany replied 9 years ago.

Hello and welcome to Just Answer

 

Please post your questions and I am sure someone will be able to help. It would also help if you quote your deadline as well as the name of the book you are using: title, author's name, and edition

 

Thank you

Customer: replied 9 years ago.

 

Week 6: Two Sample Hypothesis Testing - HW_CONF_INTERVALS

 

 

Help

 

 

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1. Solve the problem.

Given the same sample statistics, which level of confidence will produce the narrowest confidence interval? (Points: 1)
75%
85%
95%
90%


2. Solve the problem.

The grade point averages for 10 randomly selected students in a statistics class with 125 students are listed below.



What is the effect on the width of the confidence interval if the sample size is increased to 20? (Points: 1)
The width decreases.
The width remains the same.
It is impossible to tell without more information.
The width increases.


3. Solve the problem.

Find the critical value zc that corresponds to a 98% confidence level. (Points: 1)
±1.645
±1.96
±2.575
±2.33


4. Solve the problem.

Determine the margin of error if the grade point averages for 10 randomly selected students from a class of 125 students has a mean of = 2.7. Assume the grade point average of the 125 students has a mean of = 2.9. (Points: 1)
0.2
2.6
-0.2
2.8


5. Solve the problem.

A random sample of 40 students has a test score average with a standard deviation of 11.7. Find the margin of error if c = 0.98. (Points: 1)
1.81
1.85
4.31
0.68


6. Solve the problem.

A random sample of 150 students has a grade point average with a mean of 2.86 and with a standard deviation of 0.78. Construct the confidence interval for the population mean, , if c = 0.98. (Points: 1)
(2.71, 3.01)
(2.51, 3.53)
(2.31, 3.88)
(2.43, 3.79)


7. Solve the problem.

A group of 49 randomly selected students has a mean age of 22.4 years with a standard deviation of 3.8. Construct a 98% confidence interval for the population mean. (Points: 1)
(20.3, 24.5)
(21.1, 23.7)
(19.8, 25.1)
(18.8, 26.3)


8. Solve the problem.

The standard IQ test has a mean of 100 and a standard deviation of 17. We want to be 99% certain that we are within 2 IQ points of the true mean. Determine the required sample size. (Points: 1)
1
580
480
22


9. Solve the problem.

A survey of 400 non-fatal accidents showed that 152 involved the use of a cell phone. Find a point estimate for p, the population proportion of non-fatal accidents that involved the use of a cell phone. (Points: 1)
0.620
0.380
0.613
0.275


10. Solve the problem.

A survey of 250 homeless persons showed that 37 were veterans. Find a point estimate p, for the population proportion of homeless persons who are veterans. (Points: 1)
0.174
0.852
0.148
0.129


11. Solve the problem.

A survey of 300 fatal accidents showed that 123 were alcohol related. Construct a 98% confidence interval for the proportion of fatal accidents that were alcohol related.
ENTER THE ANSWER IN THE FORMAT: (#.###, #.###) With an accuracy up to third decimal place.
For example: (0.123, 0.321) (Points: 2)


12. Solve the problem.

A survey of 280 homeless persons showed that 63 were veterans. Construct a 90% confidence interval for the proportion of homeless persons who are veterans. (Points: 1)
(0.161, 0.289)
(0.176, 0.274)
(0.167, 0.283)
(0.183, 0.266)


13. Solve the problem.

A manufacturer of golf equipment wishes to estimate the number of left-handed golfers. How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 5%? A previous study indicates that the proportion of left-handed golfers is 8%. (Points: 1)
174
41
160
114


14. Solve the problem.

A researcher wishes to estimate the number of households with two cars. How large a sample is needed in order to be 90% confident that the sample proportion will not differ from the true proportion by more than 6%? A previous study indicates that the proportion of households with two cars is 23%. (Points: 1)
134
81
3
173


 

Customer: replied 9 years ago.
some body can tell me ! if you guys are available to help me or not with this i already put a deposit.....