Question

He average score for half of the students in a class on a certain test was 90.the average score for another fourth of the students was 80.if the average (arithmetic mean) score for all of the students was 78.what was the average score for the remaining students

Answer 1

let the no of students be x
avg. of x/2 students= 90
avg. of x/4 students= 80
avg. of x students= 78
avg. of remaining x/4 students
     => 78 = (90 + 80 + x)/3
     => 234 = 170 + x
     => x = 64