Random samples of 50 male and 40 female students are asked to imagine buying a Mothers Day present. We want to estimate the difference in how much they are willing to spend. We should use a . . .

Group of answer choices

two independent samples t-test.

two paired samples t-test.

two independent samples t confidence interval.

two paired samples t confidence interval.

A method to assess the effectiveness of a drug is to measure its concentration in the urine after a period of time. Twenty people are given the first brand and twenty-five are given the second brand. For the two samples, the mean concentrations in the first sample is 19.2 (mg) with standard deviations of 8.6 (mg) and the mean concentrations in the second sample is 15.6 (mg) with standard deviations of 7.8 (mg) respectively, one hour after ingestion.

Find the best point estimate.

Group of answer choices

3.6

15.6

17.4

19.2

Newborn babies are more likely to be boys than girls. A random sample found 13,173 boys were born among 25,468 newborn children. The sample proportion of boys was 0.5172 (and 0.4828 for girls). Is this sample evidence that the birth of boys is more common than the birth of girls in the entire population?

Which one of the following is the appropriate alternative hypothesis?

Group of answer choices

Ha : P_boys = P_girls

Ha : (P_boys - P_girls) = 0

Ha : P_boys < P_girls

Ha : (P_boys - P_girls) > 0

A drug company introduced a new drug, they must first convince the Food and Drug Administration (FDA) that it is a worthwhile addition to the current set of drugs. That is, they must be able to demonstrate that the new drug is better than current drugs.

which significance level should they use?

Group of answer choices

0.01

0.25

10%

15%

Side-by-side boxplot can be used to compare between . . .

Group of answer choices

one sample and population.

paired groups.

independent groups.

None of the above.