text: #include <stdio.h>
  
  int main(void)
  {
  	float marks[15] = {0};
  	float mark, sum, mean;
  	int i;
  
  	for (i = 0; i < 15;)
  	{
  		printf("Enter marks: ");
  		scanf("%f", &mark);
  
  		if (mark >= 0 && mark <= 20)
  		{
  			marks[i] = mark;
  			i++;
  		}
  	}
  
  	for (i = 0; i < 15; i++)
  	{
  		sum += marks[i];
  	}
  
  	printf("Mean is %.2f\n", sum / 15.00);
  
  	return 0;
  }
  