#include <stdio.h> float gpa(int n, float* xuefen, float* jidian) { float sum = 0, xuefensum = 0; for (int i = 0; i < n; i++) { sum += (xuefen[i] * jidian[i]); xuefensum += xuefen[i]; } return sum / xuefensum; } int main() { int n; scanf("%d", &n); float xuefen[n], score[n], jidian[n]; for (int i = 0; i < n; i++) { scanf("%f", &xuefen[i]); } for (int i = 0; i < n; i++) { scanf("%f", &score[i]); } for (int i = 0; i < n; i++) { if (score[i] >= 90) jidian[i] = 4.0; else if (score[i] >= 85) jidian[i] = 3.7; else if (score[i] >= 82) jidian[i] = 3.3; else if (score[i] >= 78) jidian[i] = 3.0; else if (score[i] >= 75) jidian[i] = 2.7; else if (score[i] >= 72) jidian[i] = 2.3; else if (score[i] >= 68) jidian[i] = 2.0; else if (score[i] >= 64) jidian[i] = 1.5; else if (score[i] >= 60) jidian[i] = 1.0; else jidian[i] = 0; } printf("%.2f", gpa(n, xuefen, jidian)); return 0; }