+(void)test
{
    double mean = 200;
    double variance = 20;
    double val=0;
    for(int i=0; i<100; i++)
    {
        val+=1;
        double result = [AnswerGenerator rangeForMean:mean variance:variance value:val];
        NSLog(@"Mean: %.1f variance: %.1f val: %.1f, result:%.1f", mean, variance, val, result);
    }
}

+(double)rangeForMean:(double)mean variance:(double)variance value:(double)x
{
    double val = (mean - x)/sqrt(variance);
    val = (val) * M_SQRT1_2;
    val = erfc(val);
    return 0.5 * val;
}