/* -*- coding: utf-8 -*-
 *
 * 1980.cc:  No.1980 [Cherry 4th Tune D] 停止距離 - yukicoder
 */

#include<cstdio>
#include<cmath>
#include<algorithm>

using namespace std;

/* constant */

const int CNT = 200;

/* typedef */

/* global variables */

double s(double v, double t, double m) {
  return v * t + v * v / (20 * m);
}

/* subroutines */

/* main */

int main() {
  int tn;
  scanf("%d", &tn);

  while (tn--) {
    double t, m, l;
    scanf("%lf%lf%lf", &t, &m, &l);

    double v0 = 0.0, v1 = 5100.0 * 1000 / 3600;
    for (int cnt = 0; cnt < CNT; cnt++) {
      double v = (v0 + v1) / 2;
      if (s(v, t, m) <= l) v0 = v;
      else v1 = v;
    }

    double v = v1 * 3600 / 1000;
    v = floor(v * 100) / 100;
    printf("%.2lf\n", v);
  }
  return 0;
}