George invited 65 students in his school to volunteer at a charity race. 39 of the students signed up to volunteer. What percent of the invited students signed up? [Type your answer as a number.]

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”?