9. Write the equation of the parabola in vertex form.

A. y = (x – 2)^2 + 4

B. y = x^2 – 4

C. y = (x – 2)^2

D. y = (x – 4)^2 – 4

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”?