实例11阳阳买苹果

#include<stdio.h>

int main()
{
 double average,sum=0.0;
 int a=2,day=0;
 while(a<=100){
  sum+=a;
  a*=2;
  day++;
 }
 average=sum*0.8/day;
 printf("%f\n", average);
 return 0;
}