Which recursive formula can be used to determine the total amount of money earned in any year based on the amount earned in the previous year? 100, 105, 110.25, ...

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”?