……c++编程作业我又不会写

参考答案：2353453465465476575675675675675234355445345435345一。1。B 2。C二。#include<iostream>using namespace std;int main(){ int i,a,n,sum=0; float av; cin >> n; for(i=0;i<n;i++) { cin >>a; sum+=a; } av=(float)sum/n; printf("%.2f\n",av);//#也可用 cout << fixed << setprecision(2) << av << endl;///但要加头文件iomanipreturn 0;}一。1。 B2。 D二。#include<iostream>using namespace std;int main(){ int i,a,n,ct=0; float r; cin >> n; for(i=0;i<n;i++) { cin >>a; if (a<500 || a>550) { cout << a << " "; ct++; } } r=(float)ct/n*100; cout << endl << r << "%" <<endl;return 0;}一。1。D2。C二。#include<iostream>#include<cstdio>#include<iomanip>using namespace std;int main(){ int i,a,n,sum=0; float av; freopen("math.in","r",stdin); freopen("math.out","w",stdout); cin >> n; for(i=0; i<n; i++) { cin >>a; sum+=a; if (a<60) printf("%d ",a); } av=(float)sum/n; printf("\n%.2f\n",av); fclose(stdin); fclose(stdout); return 0;}