Assume an investor can choose between two projects to invest in$.$ The investor knows project A will earn $5\%$ next year, while project B will earn $8\%$ next year. Assuming the two projects are of the same risk, what is the opportunity cost of capital of accepting project B$?($State your answer as a decimal such that $5\%$ should be entered as $\mathrm{.}05$ and $8\%$ should be entered as $\mathrm{.}08.)$