Chapter 6.2, Problem 24E

Which of the following probabilities are feasible for an experiment having sample space $\left\{s_1,s_2,s_3\right\}$ ? Explain your answer.

a. $\mathrm{Pr}\left(s_1\right)=.25,\mathrm{Pr}\left(s_2\right)=.25,\mathrm{Pr}\left(s_3\right)=.4$

b. $\mathrm{Pr}\left(s_1\right)=.7,\mathrm{Pr}\left(s_2\right)=.8,\mathrm{Pr}\left(s_3\right)=-.5$

c. $\mathrm{Pr}\left(s_1\right)=.2,\mathrm{Pr}\left(s_2\right)=.3,\mathrm{Pr}\left(s_3\right)=\frac{1}{2}$