You have
Working backwards with the formula for the mean i.e.
Now for the mean of both (the total)
I'm preparing for college and I got stuck on one of the problems of Pre-Algebra Placement Test.. So can someone please help me find the solution to it.
A total of 50 juniors and seniors were given a mathematics test. The 35 juniors attained an average score of 80 while the 15 seniors attained an average of 70. What was the average score for all 50 students who took the test?