Final answer:
The probability of selecting a milk chocolate or a dark chocolate is 3/4.
Step-by-step explanation:
To find the probability, we need to know the total number of chocolates in the box.
The total number of chocolates in the box is 4 + 5 + 3 = 12.
The probability of selecting a milk chocolate or a dark chocolate is the sum of the probabilities of selecting each individually.
Probability of selecting a milk chocolate = 4/12 = 1/3
Probability of selecting a dark chocolate = 5/12
Therefore, the probability of selecting a milk chocolate or a dark chocolate is 1/3 + 5/12 = 9/12 = 3/4