#include <stdio.h>
#include <math.h>

#define STUDENT_MAX (3)
#define TEST_MAX    (3)

int main (void)
{
    int  i, j;
    int  iTest[ STUDENT_MAX ][ TEST_MAX ] = 
             {{ 80, 90, 75 },
              { 30, 30, 25 },
              { 90,100, 90 }};
    float  fMean[ TEST_MAX ], fVar[ TEST_MAX ];
    float  fSD[ TEST_MAX ];

    for ( i = 0; i < TEST_MAX; i++ ) {
        fMean[i] = 0.0;
        fVar[i] = 0.0;
        fSD[i] = 0.0;
        for ( j=0; j < STUDENT_MAX; j++ ) {
            fMean[i] += ( (float)( iTest[j][i] )
                          /(float)STUDENT_MAX);
        }

        for ( j=0; j < STUDENT_MAX; j++ ) {
            fVar[i] += ( (float)( iTest[j][i] - fMean[i] ) * 
                                ( iTest[j][i] - fMean[i] ));
        }
        fVar[i] /= (float)STUDENT_MAX;
        fSD[i] = sqrt( fVar[i] );
    }

    for( i = 0; i < TEST_MAX; i++ ){
        printf( "Mean,variance,S.D. of Test[%d] \n",i+1);
        printf( "%f, ", fMean[ i ] );
        printf( "%f, ", fVar[ i ] );
        printf( "%f.\n\n", fSD[ i ] );
    }
    return  0;
}