In a random sample of 470 homeowners selected from a large suburban area, 30% indicated that they have serious problems with exessive noise from their neighbors. Estimate with 90% confidence the proportion of all homeowners in that suburban area who have this problem. (Give the confidence interval in percentages.)

Alfredo wants a 85% confidence interval for the true average gas mileage for a Gremlin after randomly sampling 9 Gremlins. It is known that the true sigma for Gremlin gas mileage is 4 mpg, and the average of the 9 Gremlins in Alfredo's study was 24 mpg. Find the confidence interval assuming the distribution is normal.

You want to get a 90% confidence interval for the difference between the percentage of females with red hair compared to males with red hair. You sample 76 females and find 34 of them have red hair. You sample 65 males and find 33 have red hair. < p1−p2 <

We wish to estimate what percent of adult residents in a certain county are parents. Out of 200 adult residents sampled, 34 had kids. Based on this, construct a 90% confidence interval for the proportion, p, of adult residents who are parents in this county. Give your answers as decimals, to three places.

A random sample of 212 high school students in a particular town showed that 56 smoke on a regular basis. Find the 95% confidence interval estimating the population percentage for smokers at this high school. Suppose the national average for smokers in high schools is 34.2%.  Does it appear that the students in this particular town smoke less than the national average?  Justify your answer

Find z* for a confidence level of 83%. Give your answer to 3 decimal places.

From a sample of 500 Pepperdine students, 205 said they commuted to school. Find the 95% confidence interval using 2 decimal places for the proportion of Pepperdine students who commute. If you use a calculator, indicate the function used and the parameters you entered for the function.