Small Test

What is the relationship between the mean of a population and the mean of the sampling distribution of the sample mean?

• They are equal.

• They are reciprocals of each other.

• The mean of the population is twice the mean of the sampling distribution.

• The mean of the sampling distribution is the square root of the population mean.

The average lot size of the houses in a small village is 55 square meters with a standard deviation of 10 square meters. Find the mean of the sampling distribution of the sample mean with a sample size of 50 houses if lot sizes are normally distributed.

• 50

• 10

• 55

• 60

A fast food chain owner claims that the average number of people who visits their store is 1350 daily with a standard deviation of 30. A random sample of 20 days showed that the average number of people who visits their store is 1400. What is the appropriate form of test statistic?

• q - test

• z - test

• t - test

• x - test

Conduct a test to determine whether or not the population proportion of voters in favor of proposal A is greater than 50%. In a random sample of 200 voters, 140 said that they were in favor of this proposal. Compute the test statistic.

• z = 6.17

• z = 5.66

• z = 19.80

• None of the above

Population or Sample?

A factory overseer selects 40 threaded rods at random from those produced that week at the factory, then she tests their tensile strength.

• Population

• Sample

The entire group studied is called the

• sample

• population

Population or Sample? A quality control engineer is curious about the thickness of paint on a car at her factory. She randomly selects 30 points on the car and measures the paint thickness at each of those points.

• Population

• Sample

A sample of 30 women finds the mean height to be 62.3 in and the standard deviation to be 1.5 in. Find the margin of error of women's heights with a 95% CL.

• 699

• 0.56

• 0.537

• 19.325

A sample of 20 cupcakes found the interval for calories to be (150, 350). Which is the correct interpretation of the 95% confidence interval?

• We are 95% confident that the true mean calorie content can be found with a sample of 150 to 350 cupcakes.

• We are 95% confident that the true mean calorie content in cupcakes is between 150 and 350 calories.

• We are 95% confident that a sample of 20 cupcakes will find 250 calories per cupcake.

• None of these are correct.

In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a standard deviation of $950. Construct a 99% confidence interval for the repair cost. 

• (1070, 2530)

• (1273, 2326)

• (1799, 1801)

• None of these.