You buy one $500 raffle ticket for a new Formula One car that valued at $15 million. Five thousand tickets are sold. What is the expected value of your gain?

Ineed asap. i cant understand this question i need someone to me right away

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

X+ 4y − z = −14 5x + 6y + 3z = 4 −2x + 7y + 2z = −17