Null hypothesis:
Alternative hypothesis:
The null is based on a recent study that 81% of the population (in this case senior citizens) takes at least one medication. The alternative hypothesis is basically the flip of the claim made in the null.
If Amelia wanted to know if the percentage was less than 81%, then the alternative would be p < 0.81
If Amelia wanted to know if the percentage was larger than 81%, then the alternative would be p > 0.81
However, she wants to know if the percentage is 81%.