The equation y=ax describes the graph of a line. if the value of a is megative the line:
a) goes down and to the left
b) goes up and to the left
c) is vertical
d) is horizontal

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”?