1. You measure 21 backpacks' weights, and find they have a mean weight of 71 ounces. Assume the population standard deviation is 4.9 ounces. Based on this, construct a 90% confidence interval for the true population mean backpack weight.
___?__ ± __?___ounces
2.The effectiveness of a blood-pressure drug is being investigated. An experimenter finds that, on average, the reduction in systolic blood pressure is 19.5 for a sample of size 605 and standard deviation 10.5.
Estimate how much the drug will lower a typical patient's systolic blood pressure (using a 98% confidence level).
Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place).
___?___< μ<___?___
3.SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first year students at your college. If you would like to limit the margin of error of your 95% confidence interval to 25 points, how many students should you sample?Make sure to give a whole number answer.
4. Out of 100 people sampled, 14 had kids. Based on this, construct a 90% confidence interval for the true population proportion of people with kids.
Give your answers as decimals, to three places
__?___ < p <___?___
5. In a survey funded by the UW school of medicine, 750 of 1000 adult Seattle residents said they did not believe they could come down with a sexually transmitted infection (STI). Construct a 95% confidence interval estimage of the proportion of adult Seattle residents who don't believe they can contract an STI. (Use a z
z - score of 1.96 for your computations.)
- A (.728, .772)
- B(.723, .777)
- C(.718, .782)
- D(.713, .878)
- E(.665, .835)
6.A political candidate has asked you to conduct a poll to determine what percentage of people support her.
If the candidate only wants a 9% margin of error at a 90% confidence level, what size of sample is needed?
Give your answer in whole people.