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

int  main(void)
{
    float  mean, variance, sd;

    mean = ( 80.0 + 90.0 + 75.0 ) / 3.0;
    variance = ( ( 80.0 - mean ) * ( 80.0 - mean ) +
                 ( 90.0 - mean ) * ( 90.0 - mean ) +
                 ( 75.0 - mean ) * ( 75.0 - mean ) ) / 3.0;
    sd = sqrt( variance );

    printf( " mean, variance, standard deviationC\n" );
    printf( "%f, ", mean );
    printf( "%f, ", variance );
    printf( "%f.\n", sd );

    return  0;
}