Answer
a. In this case, we want to support the claim, so the alternative hypothesis should represent the claim. Hence:
Null Hypothesis: $H_{o}: μ \leq 28$
Alternative Hypothesis: $H_{a}: μ \gt 28$
b. a. In this case, we want to reject the claim, so the null hypothesis should represent the claim. Hence:
Null Hypothesis: $H_{o}: μ \geq 28$
Alternative Hypothesis: $H_{a}: μ \lt 28$
Work Step by Step
As given above