An investor believes that the returns for an investment depends on the state of the economy. The following data are provided regarding each state and return.

State Probability Return

Strong $10\%15\%$

Weak $20\%-8\%$

No change $70\%10\%$

$(1)$ Calculate the expected return.

a$)1\mathrm{.}50\%$

b$)7\mathrm{.}00\%$

c$)6\mathrm{.}90\%$

d$)-1\mathrm{.}60\%$