#include "iostream"
#include "cstring"
#include "cstdio"
#include "algorithm"
#include "queue"
#include "vector"
#include "queue"
#include "stack"
#include "ctime"
#include "set"
#include "map"
#include "cmath"
using namespace std;
#define fi first
#define se second
#define vi vector<int>
#define pb push_back
#define eb emplace_back
#define pii pair<int,int>
#define mp make_pair
#define rep( i , a , b ) for( int i = (a) , i##end = b ; i <= i##end ; ++ i )
#define per( i , a , b ) for( int i = (a) , i##end = b ; i >= i##end ; -- i )
#define mem( a ) memset( a , 0 , sizeof (a) )
#define all( x ) x.begin() , x.end()
//#define int long long
typedef long long ll;
const int MAXN = 2e5 + 10;
int n , m;
int A , B;

double f[MAXN] , S[MAXN];

void solve() {
	cin >> n >> A >> B;
	vi pt;
	rep( i , 1 , B ) pt.pb( i );
//	S[1] = 2.5;
	rep( k , 1 , n ) {
		double l = 0 , r = 1e5;
		while( r - l > 1e-9 ) {
			double mid = ( l + r ) / 2;
			double a = 0 , b = 0;
			rep( i , 0 , A - 1 ) {
				double t;
				if( k > 1 ) t = min( ceil( mid * i * B * 1. / ( ( A - i ) * S[k - 1] ) ) , B * 1. );
				else t = B;
				a += t * i , b += ( A - i ) * t * ( t - 1. ) * S[k - 1] / ( B * 2 );
//				cout << t << ' ';
			}
//			puts("");
			b += B * A * A;
			if( b / a < mid ) r = mid;
			else l = mid;
		}
		f[k] = r;
		S[k] = S[k - 1] + f[k];
//	cout << f[k] << endl;
	}
	printf("%.3lf\n",S[n]);
}

signed main() {
//	freopen("in","r",stdin);
//	freopen("out","w",stdout);
	int T;cin >> T;while( T-- ) solve();
//	solve();
}