What is the probability of reaching into a bin and selecting particular color m candy?

The probability of reaching into a bin and selecting a particular color m candy depends on the total number of candies in the bin and the number of candies of that particular color.

Let's assume that there are a total of n candies in the bin and m of those candies are of the particular color you are interested in. The probability of selecting a candy of that particular color is then:

$$P(selecting\ particular\ color\ m\ candy) = \frac{m}{n}$$

For example, if there are 100 candies in a bin and 20 of those candies are red, the probability of selecting a red candy is 20/100 = 0.2 or 20%.