Multiple choice

Question 1

What is meant by the term "90% confident" when constructing a confidence interval for a mean?

a) If we took repeated samples, approximately 90% of the samples would produce the same confidence interval.

b) If we took repeated samples, the sample mean would equal the population mean in approximately 90% of the samples.

c) If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the sample mean.

d) If we took repeated samples, approximately 90% of the confidence intervals calculated from those samples would contain the true value of the population mean.

Question 2

Insurance companies are interested in knowing the population percent of drivers who always buckle up before riding in a car.

• Part (a)
• When designing a study to determine this population proportion, what is the minimum number of drivers you would need to survey to be 95% confident that the population proportion is estimated to within0.01? (Round your answer up to the nearest whole number.) _____drivers
• Part (b) Muliple choice

If it was later determined that it was important to be more than 95% confident and a new survey was commissioned, how would that affect the minimum number you would need to survey? Why?

a) If the confidence level is increased, then the sample size would not be affected.

b) If the confidence level is increased, then the sample size would need to increase because a higher level of confidence increases the margin of error.

c) If the confidence level is increased, then the sample size would need to decrease because we would like the proportion of people who buckle up to be around 50%.

d) If the confidence level is increased, then the sample size would need to decrease because increasing the sample size would create an even larger interval.

Question 3

According to a poll,76%of California adults (387out of 506 surveyed) feel that education is one of the top issues facing California. We wish to construct a 90% confidence interval for the true proportion of California adults who feel that education is one of the top issues facing California.

What is a point estimate for the true population proportion?

_____________