1.A researcher wants to estimate the proportion of a population which possess a given characteristic. A random sample of size 250 is taken and 40% of the sample possess the characteristic. The 90% confidence interval to estimate the population proportion is _______.

2.Catherine Cho, Director of Marketing Research at Vitalglow Pty Ltd, is evaluating consumer acceptance of a new toothpaste package. Her staff report that 17% of a random sample of 200 Darwin households prefer the new package to all other package designs. If Catherine concludes that 17% of all households prefer the new package, she is using a _______.

3.

A study of 200 apple trees showed that the average number of apples per tree was 1000. The standard deviation of the population is 200.

Which of the following is the 98% confidence interval for the mean number of apples for all trees?

4.A researcher conducted a study of the access speed of 45 hard drives and concluded that his maximum error of estimate was 28. If he were to conduct a second study to reduce the maximum error of estimate to 7, about how many hard drives should he include in his new sample?