P[day 1]=.3
Q[day 1]=.7
P[day 2]=.6
Q[day 2]=.4
probability it will rain the first day And not the second, OR it fails to rain on day 1 but rains on day 2 is:
when you say OR you add, when you say AND you multiply
P[1st day]Q[2nd day] + Q[1st day] P[2nd day]
.3[.4] + .7[.6]
.12+.42= .54 answer
This should be identical to 1-[rains both days OR doesn't rain on the 2 days]
You should use this to check first answer
Arthur
