Estimation

Parameters are

• numerical characteristics of a sample.

• numerical characteristics of a population.

• the averages taken from a sample.

• numerical characteristics of either a sample or a population.

Sampling distribution ΣX_i/n is

• probability distribution of the sample average

• probability distribution of the sample proportion.

• mean of the sample.

• mean of the population

A simple random sample of 100 observations was taken from a large population. The sample average and the sample standard deviation were determined to be 80 and 12 respectively. The standard deviation of the sample average is

• 1.20

• 0.12

• 8

• 0.8

A simple random sample of 144 observations was taken from a large population. The sample average and the sample standard deviation were determined to be 1234 and 120 respectively. The standard deviation of the sample average is

• 1234±120

• 120

• 1440

• 10

The following data was collected from a simple random sample of a population.

13 15 14 16 12

The mean of the population

• is 14.

• is 15.

• is 15.1581

• could be any value.

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is between 0.30 and 0.50 is

• 0.4664

• 0.9328

• 0.0336

• 0.0672

Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. Which of the following best describes the form of the sampling distribution of the sample average for this situation?

• Approximately normal because the sample size is small relative to the population size

• Approximately normal because of the central limit theorem

• Exactly normal

• None of these alternatives is correct

The following data was collected from a simple random sample of a population.

13 15 14 16 12

The point estimate of the population standard deviation is

• 2.5

• 1.581

• 2.

• 1.414

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

• 8.225

• 8.3

• 9.8

• 9.92

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

• 1.711

• 2.064

• 2.492

• 2.069