Thread: Program closes too early

My program closes immediately after carrying the for loop is terminated. Does any one know why this might be happening? Here's the for loop, I'm very inexperienced in programming so I've probably made a simple mistake...

Code:

for(i=1; i<=n_students; i++) {
        printf ("\nEnter the number of marks student %d recieved on Assignment One: ", i);
        scanf ("%lf", &ass1_mark);
            if (i == 1) ass1_av = ass1_mark;
            else ass1_av = (ass1_mark*(1/i)+ass1_av*(1-(1/i)));  
              
        printf ("\nEnter the number of marks student %d recieved on Assignment Two: ", i);
        scanf ("%lf", &ass2_mark); 
            if (i == 1) ass2_av = ass2_mark;
            else ass2_av = (ass2_mark*(1/i)+ass2_av*(1-(1/i)));  
            
        printf ("\nEnter the number of marks student %d recieved on Assignment Three: ", i);
        scanf ("%lf", &ass3_mark); 
            if (i == 1) ass3_av = ass3_mark;
            else ass3_av = (ass3_mark*(1/i)+ass3_av*(1-(1/i)));
              
        printf ("\nEnter the number of marks student %d recieved on Assignment Four: ", i);
        scanf ("%lf", &ass4_mark); 
            if (i == 1) ass4_av = ass4_mark;
            else ass4_av = (ass4_mark*(1/i)+ass4_av*(1-(1/i)));  
            
        printf ("\nEnter the number of marks student %d recieved on Assignment Five: ", i);
        scanf ("%lf", &ass5_mark); 
            if (i == 1) ass5_av = ass5_mark;
            else ass5_av = (ass5_mark*(1/i)+ass5_av*(1-(1/i)));  
            
        printf ("\nEnter the number of marks student %d recieved on the midterm: ", i);
        scanf ("%lf", &midterm); 
            if (i == 1) midterm_av = midterm;
            else midterm_av = (midterm*(1/i)+midterm_av*(1-(1/i)));  
        
        printf ("\nEnter the number of marks student %d recieved on the final: ", i);
        scanf ("%lf", &final); 
            if (i == 1) final_av = final;
            else final_av = (final*(1/i)+final_av*(1-(1/i))); 
        }

Thank you!!