Answer:
Three
Step-by-step explanation:
Assuming the grade score from 70 to 100 is A; for grade score from 60 to 69 is B and grade score from 50 to 59 is C. Well it is certain there are three peaks in the distribution of scores
25a-20
15a+10a-20=
x = 150
1/3 x = 50
x -20 = 30
x -10 = 140
Are u ok ????