Samantha ate 2/5 of the 30 cookies her mother made, and her father Ben ate 2/3 of the remainder. How many of the cookies had been eaten?

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”?