How to solve this?

Statistics and Probability Content: Random Variables and Probability Distributions Competencies 5. Illustrates the mean and variance of a discrete random variable 6. Calculates the mean and the variance of a discrete random variable 7. Interprets the mean and the variance of a discrete random variable 8. Solves problems involving mean and variance of probability distributions Problem Solving 1. At a raffle, 1500 tickets are sold at P50 each for four prizes P5000, P2500, P1500, and P750. You buy one ticket. What is the expected value of your gain?5. Your father said, if in one semester your general average is 90 and above, he will add 100 Php to your daily allowance, 50 Php if your average is 85 to 89, but decrease it by 20 Php if your grade is 84 and below. If the probability to get 90 and above is 18.5%, while you have 43% chance to get 85 to 89, what is your expected allowance per semester? What is the standard deviation of your possible allowance