Question

The average score of students in a test was 64. Top 20% of them secured an average score of 80 and the bottom 20% secured an average score of 30, What is the average score of remaining percentage of students?

Answer 1

let us assume the number of students in the class is 100x.

therefore,
sum of all scores of the whole class is 6400x;
sum of scores of top 20% is 1600x;
sum of scores of bottom 20% is 600x

so sum of remaining students' scores is 6400x - 1600x - 600x = 4200x
number of remaining students = 60x
4200x ÷ 60x = 70
avg. score of remaining students is 70.