#include <iostream>
#include <iomanip>
using namespace std;
using ll = long long;

int main(){
    int T;
    cin >> T;
    while (T--){
        ll N, M, K;
        cin >> N >> M >> K;
        if (K <= M * (N - 1)){
            ll lceil = (K + M - 1) / M;
            cout << setprecision(15) << 1.0 - (double)lceil / (double)(N * M) << endl;
        }
        else{
            cout << setprecision(15) << (double)(M * N - K) / (double) M << endl;
        }
    }
}