This is an example of a problem involving mutually exclusive events, which are events that cannot occur at the same time. There is no way that a marble picked is red AND yellow at the same time, right? That's why the problem uses an OR.
To solve problems involving mutually exclusive events, we use the formula
P(A or B) = P(A) + P(B). We will translate this in our problem as the probability of picking a red marble + the probability of picking a yellow marble.
(a) The probability of picking a red marble is [tex] \frac{14}{44} [/tex] .
(b) The probability of picking a yellow marble is [tex] \frac{18}{44} [/tex].
Therefore, The probability of picking a red or a yellow marble is
P(A or B) = [tex] \frac{14}{44}+ \frac{18}{44} = \frac{32}{44} [/tex] or [tex] \frac{8}{11} [/tex] ≈ 0.73.
