Question

Find the probability that 3 or 4 cars have been sold in a day

$$\begin{array}{c:c} x &Pr(X=x) \\ \hdashline 0 & 0.25 \\ \hdashline 1 & 0.2\\ \hdashline 2 & 0.15\\ \hdashline 3 & 0.1\\ \hdashline 4 & 0.15 \\ \hdashline 5 & 0.15 \end{array}$$

Answer 1

$$P(X=3\ or\ X=4)=P(X=3)+P(X=4)$$

$$=0.1+0.15=0.25$$

The probability that 3 or 4 cars have been sold in a day is 0.25.