Answer:
The third quiz grade is 18 points.
Explanation:
It is given that the average of 3 quiz grades is 17 points.
First quiz grade = 14
Second quiz grade = 19
Let x be the third quiz grades.
Average formula:

Average of three quiz grade is



Multiply both sides by 3.


Subtract 33 from both sides.


Therefore the third quiz grade is 18 points.