1. Write the null and alternative hypotheses for each of the following examples. Determine if each is a

case of a two-tailed, a left-tailed, or a right-tailed test. [2x5=10]

a. Working on an average at least 5 hours per day at a computer contributes to deterioration of

eyesight.

b. It is thought that 12% of all students taking a particular course received a grade of A. In a

sample of 155 students, it is found that 21 made an A.

c. A statistical study considers the question of whether the presence of plants in an office might

lead to fewer sick days. Current average sick days is 3 days per month.

d. In an average week, how many hours of TV/movies/online "stuff", etc. do students watch? Is

it different than 10 hours?

e. Suppose a businessperson wishes to open a store in a local shopping center only if there is

strong evidence that the average number of people in the center is greater than 5000 per day