Let:
Event A: Rain
Event B: mostly cloudly
Then, the probability (P) of the events occurring is:
P(A) = 0.71
P(B) = 0.75
P(A and B) = 0.85
Since the events are non-mutually exclusive, P(A or B) can be found using the formula below:
[tex]P(A\text{ }or\text{ }B)=P(A)+P(B)-P(A\text{ }and\text{ }B)[/tex]
The probability that it will be mostly cloudy or it will rain is P(A or B), substituting the values, we have:
[tex]\begin{gathered} P(A\text{ }or\text{ }B)=71+75-85 \\ P(A\text{ }or\text{ }B)=61percent \end{gathered}[/tex]
Answer: 61%.