Read carefully and click the option that has the correct answer of the question. If xy = 0, which of the following statements is true? A x must equal 0.
B y must equal 0. Either x or y
C must be equal to 0.
D Both x and y must be equal to 0. Or
E Neither x nor y equals 0.

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”?