Question

QUESTION 1:

In a randomized comparative experiment on the effect of color on the performance of a cognitive task, researchers randomly divided 71 subjects (29 males and 42 females ranging in age from 17 to 25 years) into three groups. Participants were asked to solve a series of 6 anagrams. One group was presented with the anagrams on a blue screen; one group saw them on a red screen; and one group had a neutral screen. The time, in seconds, taken to solve the anagrams was recorded. The paper reporting the study gives x¯¯¯=x¯=11.63 and s=s=4.17 for the times of the 26 members of the neutral group.

(Give your answer to three decimal places.)

A 90% confidence interval for the mean time in the population from which the subjects were recruited is from  to  seconds.

QUESTION 2:

A veterinarian wishes to compare the number of times race horses are reported to be lame during a 12-month period compared with similar horses that are not raced. The veterinarian is particularly interested whether the exercise schedule used in racing may contribute to lameness rather than the total amount of exercise. The veterinarian chooses 9 race horses and then selects for each race horse chosen a horse used in jumping that is the same age, breed, and exercises a similar number of hours each week. The table below contains the observed number of times a horse was lame.

Horse

Group	1	2	3	4	5	6	7	8	9
Race	7	8	2	0	3	1	4	2	6
Jump	2	1	3	2	4	1	3	7	4

A 90% confidence interval for the mean difference in the number of times a horse is lame is given by:

	(–1.590, 2.923).
	(–1.329, 2.663).
	(–3.405, 4.738).
	(–2.459, 3.792).

Answer 1