Question

1. In a survey, 14 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $44 and a standard deviation of $10. Construct a confidence interval at a 99% confidence level. Give your answers to one decimal place.
___ ± ___

2. The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 50 for a sample of size 12 and standard deviation 15. Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 98% confidence level). Give your answers to one decimal place and provide the point estimate with its margin of error.

___ ± ___

3. In a survey, 31 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $31 and a standard deviation (s) of $14. Construct a confidence interval at a 99% confidence level. Give your answers to one decimal place.
___±___

4. Express the confidence interval (61%,67.8%) in the form of p^±ME.

___% ±___ %

5. A political candidate has asked you to conduct a poll to determine what percentage of people support her. If the candidate only wants an 8% margin of error at a 99% confidence level, what size of a sample is needed?Give your answer in whole people

ANSWER ALL QUESTIONS PLEASE!

Answer 1

1) The CI for mean is .

Here ,. The R command for finding the critical value is

> qt(0.0005,13)
[1] -4.220832

The 99% CI is

2) The CI for mean is .

Here ,. The R command for finding the critical value is

> qt(0.001,11)
[1] -4.024701
>

The 98% CI is

3) The CI for mean is .

Here ,. The R command for finding the critical value is

> qt(0.0005,13)
[1] -4.220832

The 99% CI is

4) We know

Henec,

5) Where is standard deviation ? Its value os needed because