import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.List;
public class Solution {
public static void main(String[] args) {
List scores = Arrays.asList(92, 85, 85, 85, 89, 91, 93, 92,90,86,
91, 93, 96, 90, 90);
List credits = Arrays.asList(1 ,1, 1, 2, 2, 2, 2, 2,
2 ,2, 2, 2, 2, 2, 2);
assert scores.size() == credits.size();
int sumScore = 0;
int sumCredit = 0;
for (int i = 0; i < scores.size(); i++) {
sumScore += scores.get(i) * credits.get(i);
sumCredit += credits.get(i);
}
System.out.println((double) sumScore / (double) sumCredit);
}
}