Which could be the entire interval over which the function, f(x), is positive?

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”?

Which answer goes into the box? (90° clockwise rotation, 90° counter clockwise rotation, translation, or glide reflection)

Why is causation so much more difficult to prove than correlation?