Odds in favor = successes:failures
Odds against = failures:successes
Probability of success =
Probability of failure =
You have the odds in favor of snow tomorrow as 3:5.
So "it will snow tomorrow" is considered a SUCCESS and
"it will NOT snow tomorrow" is considered a FAILURE.
Therefore successes = 3 and failures = 5
The probability that it will NOT snow tomorrow is the probability of a failure:
Probability of failure = = =
Edwin