dolphin jet ski shop charges a flat fee of $37.00 plus $1.25 per hour to rent a jet ski. Marlin Jet Ski charges a fee of $30.00 plus $3.00 per hour to rent the same jet ski. Find the number of hours for which the costs are the same

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”?