In the sentence below, which word refers to a mathematical operation? jane has 3 dollars per dollar mark has. a. 3 b. dollars c. per d. the sentence references no mathematical operation

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”?