Which of the expressions are equivalent to the one below? Check all that apply.

3. (1+5) + 6.9

A. 3. (5 + 1) + (69)

B. (6.9) + 3. (5 + 1)

C.3.1 +3.5+ 9.6

D. (3 + 1). (3 + 5) + (69)

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”?