#include <iostream> #include <string> #include <algorithm> #include <cstdio> using namespace std; const int N = 10; int n; int a[N], b[N]; float c[N];//a[i]为学分,b[i]为得分,c[i]为绩点 float GPA; int sum; int main() { cin >> n; for (int i = 0; i < n; i++) cin >> a[i]; for (int i = 0; i < n; i++) { cin >> b[i]; if (b[i] >= 90) c[i] = 4.0; else if (b[i] >= 85) c[i] = 3.7; else if (b[i] >= 82) c[i] = 3.3; else if (b[i] >= 78) c[i] = 3.0; else if (b[i] >= 75) c[i] = 2.7; else if (b[i] >= 72) c[i] = 2.3; else if (b[i] >= 68) c[i] = 2.0; else if (b[i] >= 64) c[i] = 1.5; else if (b[i] >= 60) c[i] = 1.0; else c[i] = 0; } for (int i = 0; i < n; i++) { GPA +=(a[i] * c[i]); sum += a[i]; } GPA = GPA / sum; printf("%.2f", GPA); return 0; }