There is a 40 percent chance of rain today and a 50 percent chance of rain tomorrow. If the two events are independent, what is the probability that it will rain today or tomorrow?

Question

anonymous · Answer

You need three events here:
the probability it rains today and not tomorrow (.5)(.6)
the probability it rains tomorrow and not today (.5)(.4)
and the probability it rains both days (.5)(.4)
add all those up to get a total of 0.70 or 70 percent

anonymous · Answer

if they are independent then the probability that they both happen is the produce.  
$$P(A\cup B)=P(A)+P(B)-P(A\cap B)$$
the first two you know, the last one you get by multiplying.

anonymous · Answer

Ohhhhhh I did this a while ago in class, thanks

anonymous · Answer

$$P(A\cup B)=.4+.5-.4\times .5=.7$$