19. Catching a Cold, again Refer to Exercise 18

(

Section 8.5). The percentage of people catching a cold when exposed to a cold virus is shown in the table, for a group of people with only a few social contacts and a group with six or more activities.

Construct a 95% lower confidence bound for the difference in population proportions. Does it appear that when exposed to a cold virus, a greater proportion of those with fewer social contacts contracted a cold? Is this counter-intuitive?

Sample Size Percent with Colds Few Social Outlets Many Social Outlets 96 62% 105 35%