A researcher wants to decide whether the average Statistics 101 course exam scores of students of faculty of engineering and faculty of natural sciences are same or not. He takes 60 students from faculty of engineering whose average exam score is 59, and 50 students from faculty of natural sciences whose average score is 65. The variance regarding the exam scores for engineering faculty is 15, and that for natural sciences faculty is 10. What will be the z-statistics for this comparison?