27) if a = 1/a
multiply both sides by a
a * a = 1/a * a
a^ 2 = 1
Answer is D) 1
28)
6 x 75 = 450
7 x 80 = 560
8 x 85 = 680
9 x 90 = 810
Total all students in class = 6 + 7 + 8 + 9 = 30 students
Total score of whole class:
450 + 560 + 680 + 810 = 2500
Average = 2500 /30 = 83.3 = 83 1/3
Answer is C) 83 1/3