here please:

Consider the following grading system: Based on the previous years, we know that the professor grades an exam work as "very gnod'1 with a probability of {12; as 1"good" with a probabilit},r of 0.35; and as "satisfactory\" with a probability of 0.25. Consider a random variable A describing the distribution of grades in the exam. What are the probabilities of pasting; an exam with other grades {according to the table] if we know that the expected value of a random 1variable A is equal to 2.5