I Believe There Is A $60 \%$ Chance That Toilet Paper Is Going on Sale Tomorrow For Paper

Short Answer

I believe there is a $60 \%$ chance that toilet paper is going on sale tomorrow for $\$ .75$ per roll and a $40 \%$ chance that it will not and cost $\$ 2$ per roll. Unfortunately, I have to place an order today. I have $\$ 10$ to spend on toilet paper.
a. Given my beliefs, how many rolls do I order?
b. If I receive insider information from the store that toilet paper will definitely be on sale, how many rolls do I order? (Suppose you can order fractions of a roll.)
c. If I receive insider information from the story that toilet paper will definitely not be on sale, how many rolls do I order?