Question 974102
The 35 juniors attained an average score of 80 = 80 *35 = 2800
The 15 seniors  obtained an average of 70 = 70 * 15 = 1050
The total score for all 50 students who took the test = 2800 + 1050 =3850
The average score for all 50 students who took the test = 3850/50 = 77