#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
#define drep(i, cc, n) for (ll i = (cc); i <= (n); ++i)
#define rep(i, n) drep(i, 0, n - 1)
#define all(a) (a).begin(), (a).end()
#define pb push_back
#define fi first
#define se second

const ll MOD = 1000000007;
const ll MOD2 = 998244353;
const ll INF = 1LL << 60;
const ll N_MAX = 2e5;

double solve(){
    double t, u, l;
    cin >> t >> u >> l;

    t=t/3600;
    l=l/1000;
    u=(u*3600*3600)/1000;

    double lo = 0;
    double hi = 1000000;
    double mid;
    ll loop = 0;
    while(hi - lo > 0.00000001){
        mid = (lo + hi)/2;
        loop++;
        if(loop == 100) break;
        if(mid*mid+20*u*t*mid-20*u*l > 0) hi = mid;
        else lo = mid;
    }

    lo = lo*pow(10, 7);
    lo = round(lo);
    lo /= pow(10, 7);
    
    return lo;
}

int main(){
    ll n;
    cin >> n;

    vector<double> ans(n);
    rep(i, n) ans[i] = solve();
    rep(i, n) cout << fixed << setprecision(2) << floor(ans[i]*100)/100 << endl;
}