Determine the measure of ∠R, rounded to the nearest tenth of a degree. A)

129.9°

B)

50.1°

C)

39.9°

D)

44.7°

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”?