Confidence interval estimate of population proportion

1. Of 900 customers surveyed, 414 said they were very enthusiastic about a new home décor scheme. Construct a 99 percent confidence interval estimate of the population proportion. Interpret your answer.

2. A sample of 49 vehicles are taken, measuring the speed of the vehicle at a specific point. The sample mean was 55, and the standard deviation for the sample was 10. What is the 90 percent confidence interval estimate of the mean speed of vehicles at this point?

3. The attendance at the Nashville minor league baseball game last night was 400. A random sample of 50 of those in attendance revealed that the mean number of soft drinks consumed was 3.24, with a standard deviation of 0.50. Develop a 95 percent confidence interval estimate of the mean. Interpret your answer.

4. A sample survey of the 256 largest companies in the U.S. found that 23 percent had told their employees how the economic downturn in early 2001 would affect the organization. Can you form a 99 percent confidence interval estimate of the proportion of all firms in the U.S. that informs their employees of the effects of recession?