The Probability that it will rain today is 0.51 and the probability that it will not rain today is 0.40
Either it will rain or it will not rain, so
.51 + .40 ≠ 1 , your statement is false
To find the probability of rain today, subtract the probability of it not raining from 1:
1 - 0.40 = 0.60.
Therefore, the probability of rain today is 0.60 or 60%.