#include <bits/stdc++.h>
using namespace std;
#define rep(i, x, limit) for (long long i = (long long)x; i < (long long)limit; i++)
#define REP(i, x, limit) for (long long i = (long long)x; i <= (long long)limit; i++)
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define el endl
#define spa " "
#define Yes cout << "Yes" << el
#define No cout << "No" << el
#define YES cout << "YES" << el
#define NO cout << "NO" << el
#define inp(x) for(auto &i:x)cin>>i
#define eps (1e-10)
#define Equals(a,b) (fabs((a) - (b)) < eps )
#define debug(x) cerr << #x << " = " << x << el
using ll = long long;
using ull = unsigned long long;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vvl = vector<vector<ll>>;
using vs = vector<string>;
using vb = vector<bool>;
const double pi = 3.141592653589793238;
const int inf = 1073741823;
const ll infl = 1LL << 60;
const string ABC = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const string abc = "abcdefghijklmnopqrstuvwxyz";
const ll MOD = 998244353;
#include<atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using vm = vector<mint>;
using ll = long long;
using i128 = __int128_t;

double prob(ll n, ll m, ll k) {
    if (k <= 0) return 1.0;
    if (n == 0) return 1.0 * k / (m - 1);  
    i128 cArg128 = (i128)k - (i128)m * (n - 1) - 1;
    ll cArg;
    if (cArg128 < -(i128)4e18) cArg = (ll)-4e18;
    else if (cArg128 > (i128)4e18) cArg = (ll)4e18;
    else cArg = (ll)cArg128;
    double C = (cArg <= 0 ? 1.0 : 1.0 * cArg / (m - 1));
    ll t = (k + m - 1) / m;
    ll r0 = max(0LL, n - t);

    return (1.0 * r0 + 1.0 * (n - r0) * (m - 1) / m * C) / n;
}
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  ll t;cin>>t;
  while(t--){
    ll n,m,k;cin>>n>>m>>k;
    cout<<fixed<<setprecision(10)<<prob(n,m,k)<<el;
  }
}