3) You are being asked to translate a numerical value to a subjective statement. There are no hard-and-fast rules for this. Generally, the meanings of the terms you're asked to choose from are ...
impossible: probability is zero. The outcome cannot occur.
unlikely: chances are less than even; often, "unlikely" means a probability of 10%, 5%, 1% or lower, depending on the context.
equally likely: probability is near 50%
likely: more likely than not. Again, this depends on the context.
certain: probability is 1. There is no chance the outcome will not occur.
An 80% probability is greater than 50%, so might reasonably be called "likely."
___
4) a. Four of the eight numbers are even, so the probability of obtaining an even number at random is 4/8 = 1/2.
b. A probability of 50% might reasonably be called "equally likely", as the probability the event will occur is equal to the probability it won't.
