Erika calculated that she would spend $115 on school supplies this year. she actually spent $82.50 on school supplies. what is erika’s percent of error?

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”?