SOLUTION: the total of 50 juniors and seniors were given a math test. the 35 juniors averaged a score of 80, while the 15 seniors averaged a score of 70. What was the average score for all 5

Algebra ->  Average -> SOLUTION: the total of 50 juniors and seniors were given a math test. the 35 juniors averaged a score of 80, while the 15 seniors averaged a score of 70. What was the average score for all 5      Log On


   

Question 144567: the total of 50 juniors and seniors were given a math test. the 35 juniors averaged a score of 80, while the 15 seniors averaged a score of 70. What was the average score for all 50 students?
Found 2 solutions by checkley77, josmiceli:
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
(35*80+15*70)/50
(2800+1050)/50
3850/50=77 is the average for both grades.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The average is the sum of all the scores divided by the number of students
either junior or senior.
Let sum of junior scores = x%5Bj%5D
Let sum of senior scores = x%5Bs%5D
Let aveage score for all 50 students = a
x%5Bj%5D%2F35+=+80
x%5Bs%5D%2F15+=+70
x%5Bj%5D+=+35%2A80
x%5Bs%5D+=+15%2A70
a+=+%28x%5Bj%5D+%2B+x%5Bs%5D%29%2F+50
a+=+%2835%2A80+%2B+15%2A70%29%2F50
a+=+2800+%2B+1050%29%2F50
a+=+3850%2F50
a+=+77
The average score for all 50 students was 77