91影视

According to the information, consider $A$as an event indicating that the first digit is $7$or higher The following are the consequences of event A:

$\text{Outcomes}=\{7,8,9\}$

$P\left(A\right)$can be calculated as:

localid="1649993368336" $$\begin{gathered} P\left(A\right)=P(X=7)+P(X=8)+P(X=9) \\ =0.058+0.051+0.046 \\ =0.155 \end{gathered}$$

Given that the probability distribution

$\begin{array}{|lcccccccc|}\hline \text{Days}& 0& 1& 2& 3& 4& 5& 6& 7\\ \text{Probability}& 0.68& 0.05& 0.07& 0.08& 0.05& 0.04& 0.01& 0.02\\ \hline\end{array}$

If $B$is the event indicating that the first digit is odd, The results of event$B$can be written as follows:

$\text{Outcomes}=\{1,3,5,7,9\}$

$\mathit{P}\left(\mathit{B}\right)$can be calculated as:

localid="1649993375643" $$\begin{gathered} P\left(B\right)=P(X=1)+P(X=3)+P(X=5)+P(X=7)+P(X=9) \\ =0.301+0.125+0.079+0.058+0.046 \\ =0.609 \end{gathered}$$

Given that the probability distribution

$\begin{array}{|lcccccccc|}\hline \text{Days}& 0& 1& 2& 3& 4& 5& 6& 7\\ \text{Probability}& 0.68& 0.05& 0.07& 0.08& 0.05& 0.04& 0.01& 0.02\\ \hline\end{array}$

The outcomes for events $A$and $B$can be written as follows, using the data from the previous sections:

$\text{Outcomes}=\{1,3,5,7,8,9\}$

$\mathit{P}(\mathit{A}$or $B)$can be calculated as:

localid="1649993383176" $$\begin{gathered} P(AorB)=P\mathit{(}X\mathit{=}\mathit{1}\mathit{)}\mathit{+}P\mathit{(}X\mathit{=}\mathit{3}\mathit{)}\mathit{+}P\mathit{(}X\mathit{=}\mathit{5}\mathit{)}\mathit{+}P\mathit{(}X\mathit{=}\mathit{7}\mathit{)}\mathit{+}P\mathit{(}X\mathit{=}\mathit{8}\mathit{)}\mathit{+}P\mathit{(}X\mathit{=}\mathit{9}\mathit{)} \\ \mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{=}\mathit{0.301}\mathit{+}\mathit{0.125}\mathit{+}\mathit{0.079}\mathit{+}\mathit{0.058}\mathit{+}\mathit{0.051}\mathit{+}\mathit{0.046} \\ \mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{}\mathit{=}\mathit{0.660} \end{gathered}$$

localid="1649993386761" $\text{Here,}P\left(A\text{or}B\right)鈮�P\left(A\right)+P\left(B\right)\text{because the events are not mutually exclusive.}$