Question

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?

Answer 1

when dealing with independent events, the probability of one event occurring does not affect the probability of another event occurring

Answer 2

Here you have \[P(rain today) = 40%\] while \[P(rain tomorrow) = 50%\]

Answer 3

the probability of two independent events occurring is the product of their probabilities: \[P(raintoday)*P(raintomorrow) = P(rain today and tomorrow)\]

Answer 4

that would b 2000

Answer 5

2000%?

Answer 6

doesnt the term "or" indicate addition of probabilities?

Answer 7

err

Answer 8

haha, yes!

Answer 9

sorry, I was giving you the answer for how to determine if both events occur

Answer 10

so, as amistre pointed out "or" implies addition while "and" implies multiplication

Answer 11

so, you actually want to \[P(raintoday) + P(raintomorrow) = P(rain today and tomorrow)\]

Answer 12

I believe

Answer 13

that looks better, and since the events are independant there is no need to subtract out the P(AnB), maybe

Answer 14

right, so, \[P(A or B) = P(A) + P(B) - P(AandB)\] and independence implies that \[P(AandB)=0\]