Estimating the Difference between Two Population Proportions Answers

is notmay be✔ is

Random condition: met 10% condition: met Large Counts condition: met All conditions for inference are met.Random condition: not met 10% condition: met Large Counts condition: met All conditions for inference are not metRandom condition: met 10% condition: does not apply Large Counts condition: met All conditions for inference are met.Random condition: met 10% condition: met Large Counts condition: not met All conditions for inference are not met.

Construct a 90% confidence interval to estimate the true difference in proportions pC – pD of caffeinated customers who order larges versus decaf customers who order larges.

Researchers want to test a new hand exercise plan for arthritis patients to see if they have improved flexibility. They recruited 110 patients with arthritis in their hands and randomly assigned them to one of two treatment groups: group 1 took their regular medicine and did the new hand exercises; and group 2 only took medicine. After one month, 42 of the 55 in group 1 improved in their flexibility, and 37 of the 55 in group 2 improved their flexibility.Construct a 95% confidence interval to estimate the true difference in proportion pex – pnoex of patients like these who would show improvement in flexibility if they did the new hand exercises along with taking the medicine versus just taking the medicine.

Construct a 99% confidence interval to estimate the true difference in the proportion of “big” bank customers who bank with more than one bank as compared with the “small” customers who bank with more than one bank.

We are 90% sure✔ We are 90% confidentWe are 90% certainThere’s a 90% probability

1.9602✔ 2.576

(0.270, 0.370)(0.038, 0.162)✔ (0.048, 0.152)

120160✔ 200300

✔ would orderordereddid order

120160200✔ 300

A bank wants to estimate the difference in the proportion of its "big" customers who have a second account with a different bank and the proportion of its "small" customers who also have an account with another bank. Of the 200 “big” customers who were randomly selected, 160 claimed to also bank with other banks. Of the 300 “small” customers who were randomly selected, 120 claimed to also bank with other banks.