Question

In a certain region, many of the residents are employed by the oil industry. Economists in the region investigated the difference between the salaries of those who work in oil-field jobs and those who work in non-oil-field jobs. Salaries were recorded for a random sample of 84 workers from the 1,200 oil-field workers and a random sample of 72 workers from the 50,000 non-oil-field workers in the region. A 95 percent confidence interval for μO−μN, where μO is the mean salary of all jobs of oil-field workers and μN is the mean salary of all jobs of non-oil-field workers, will be constructed. Have the conditions for inference with a confidence interval been met?
A: Yes, all conditions have been met.

B: No, the data were not collected using a random method.

C: No, the size of at least one of the samples is greater than 10 percent of the population.

D: No, the sample sizes are not large enough to assume the distribution of the difference in sample means is normal.

E: No, the sample sizes are not the same.

Answer 1

Answer:

The answer is A: Yes, all conditions have been met.

Random: Stated

Independent: None of the samples are greater then 10 percent of total population

Normal: n>30 so its assumed to be normal.

Sample sizes don't have to be the same unless it is a Matched pair test.

Explanation: