#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
constexpr int INF = 0x3f3f3f3f;
constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL;
constexpr double EPS = 1e-8;
constexpr int MOD = 1000000007;
// constexpr int MOD = 998244353;
constexpr int DY4[]{1, 0, -1, 0}, DX4[]{0, -1, 0, 1};
constexpr int DY8[]{1, 1, 0, -1, -1, -1, 0, 1};
constexpr int DX8[]{0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U>
inline bool chmax(T& a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U>
inline bool chmin(T& a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    std::cin.tie(nullptr);
    std::ios_base::sync_with_stdio(false);
    std::cout << fixed << setprecision(20);
  }
} iosetup;

int input() {
  string s; cin >> s;
  s.erase(prev(s.end(), 3));
  return stoi(s);
}

void solve() {
  const int t = input(), mu = input(), l = input();
  int lb = 0, ub = 5100 * 100 + 1;
  while (ub - lb > 1) {
    const int mid = (lb + ub) / 2;
    (50LL * mid * mid + 36LL * mu * mid * t - 12960LL * mu * l <= 0 ? lb : ub) = mid;
  }
  string ans = to_string(lb);
  if (ans.length() == 1) {
    ans = "0.0" + ans;
  } else if (ans.length() == 2) {
    ans = "0." + ans;
  } else {
    ans = ans.substr(0, ans.length() - 2) + '.' + ans.substr(ans.length() - 2);
  }
  cout << ans << '\n';
}

int main() {
  int n; cin >> n;
  while (n--) solve();
  return 0;
}