Final answer:
Based on the information provided, the sum of a and b suggests a total probability of 1.0, indicating certainty, under the assumption that they represent collectively exhaustive probabilities of mutually exclusive events. Typically, additional context would be needed for a correct calculation, and probabilities should be rounded to four decimal places.
Step-by-step explanation:
The question appears to be asking for the probability of either event a or event b occurring, which suggests that we should calculate P(a OR b). However, given that a and b are not defined as events, but rather as probabilities, we can interpret the question as looking for the sum of two probabilities. In standard probability theory, the sum of probabilities of two mutually exclusive events is the probability that one event or the other will occur. But it is important to note that without further context, we cannot assume events a and b are mutually exclusive or not. If we simply add the probabilities a + b, we have:
- P(a) = 0.4
- P(b) = 0.6
- P(a) + P(b) = 0.4 + 0.6 = 1.0
The combined probability in this case would simply be the sum, which is 1.0, representing certainty that one of the events will happen, assuming they are collectively exhaustive.
This interpretation may not be what the question originally intended, and typically, additional context is necessary for a correct probability calculation. It is also important that when solving relative frequency and probability problems, values are to be rounded to four decimal places if needed; however, in this case, rounding is not necessary as the sum is a whole number.