Exam 3 Warm Up

A simple random sample of size 20 is obtained from a population that is skewed left with a mean of 44 and a standard deviation of 3. A normal distribution can be used to approximate the sampling distribution.

• True

• False

Suppose that a study of elementary school students reports that the mean age at which children begin reading is 5.5 years with a standard deviation of 1.0 years. If a sampling distribution is created using samples of the ages at which 46 children begin reading, what would be the mean of the sampling distribution of sample means? Round to two decimal places, if necessary.

Suppose that a study of elementary school students reports that the mean age at which children begin reading is 5.5 years with a standard deviation of 1.0 years. If a sampling distribution is created using samples of the ages at which 46 children begin reading, what would be the standard deviation of the sampling distribution of sample means? Round to two decimal places, if necessary.

As part of a fuel efficiency study, a large school district wishes to estimate the average weekly mileage for its school buses. A sample of 28 buses is selected at random and the mileages are recorded for that week. The sample mean was found to be 210 miles with a standard deviation of 28 miles. Assume that the population distribution is approximately normal. Find the critical value that should be used in constructing a 95% confidence interval. Round your answer to three decimal places.

The American Heart Association is about to conduct an anti-smoking 23 campaign and wants to know the fraction of Americans over  who smoke. Suppose a sample of 3145 Americans over 23 is drawn.  Of these people, 789 smoke.  Using the data, estimate the proportion of Americans over  who smoke.  Enter your answer as a fraction or a decimal number rounded to three decimal places.

A simple random sample of size 28 is obtained from a population that is normally distributed with a mean of 68 and a standard deviation of 5. A normal distribution can be used to approximate the sampling distribution of sample means.

• True

• False

A simple random sample of 34 Oxford commuters found that the mean distance commuters drove to work each day was estimated to be 44.9 miles with a standard deviation of 4.4 miles. Find the critical value that should be used in constructing a 90% confidence interval. Round your answer to three decimal places.

Out of 159  randomly selected adults in the United States who were surveyed,  81 exercise on a regular basis. Using the data, estimate the proportion of adults in the United States who exercise on a regular basis. Round your answer to three decimal places