14. An article in a Florida newspaper reported on the topics that teenagers most want to discuss with their parents.
Results of poll:
46% would like more discussion about the family's financial situation
37% would like to talk about school
39% would like to talk about religion
Percentages were based on a national sampling of 513 teenagers.
Estimate the proportion of all teenagers who want more family discussions about school.
Use a 90% confidence level.
Solution: The 90% confidence interval is
15. A new cigarette has been marketed.
FDA tests on cigarette:
Mean nicotine content: 28.7 milligrams
Standard deviation: 2.4 milligrams
for a Sample of n = 9 cigarettes
Construct a confidence interval for the mean nicotine content of this brand of cigarette.
Solution: The 95% confidence interval is
16. Desiring to purchase a new car. Point to consider: resale value of the car after 5 yrs. of ownership. I decide to estimate the resale value of the car with a 99% confidence interval. You manage to obtain data on 17 recently resold 5-year old foreign sedans of that model. The 17 cars were resold:
At an avg. price of $12,700
Standard deviation: $600
What is the correct form of a 99% confidence interval for the true mean resale value of a 5-year old specific foreign sedan?
Solution: The 99% confidence interval is