The probability of rolling an odd number or a number less than 5 is 5/6.
Probability is the likelihood of the occurrence of an event. It is the ratio of number of events to number of possible outcomes.
The possible outcome from rolling a six-sided die is 1, 2, 3, 4, 5 and 6
P(odd number) = 3/6; P(less than 5) = 4/6; P(odd number and less than 5) = 2/6
Hence:
P(odd number or less than 5) = 3/6 + 4/6 - 2/6 = 5/6
The probability of rolling an odd number or a number less than 5 is 5/6.