#include <bits/stdc++.h>

using namespace std;
using ll = long long;
// #define int ll
using PII = pair<ll, ll>;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()

template<typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template<typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<typename T> bool IN(T a, T b, T x) { return a<=x&&x<b; }
template<typename T> T ceil(T a, T b) { return a/b + !!(a%b); }

template<typename T> vector<T> make_v(size_t a) { return vector<T>(a); }
template<typename T,typename... Ts>
auto make_v(size_t a,Ts... ts) {
    return vector<decltype(make_v<T>(ts...))>(a,make_v<T>(ts...));
}
template<typename T,typename V> typename enable_if<is_class<T>::value==0>::type
fill_v(T &t, const V &v) { t=v; }
template<typename T,typename V> typename enable_if<is_class<T>::value!=0>::type
fill_v(T &t, const V &v ) { for(auto &e:t) fill_v(e,v); }

template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a) {
    out<<'('<<a.first<<','<<a.second<<')'; return out;
}
template<class T>
ostream &operator <<(ostream& out,const vector<T>& a){
    out<<'[';
    for(const T &i: a) out<<i<<',';
    out<<']';
    return out;
}
template<class T>
ostream &operator <<(ostream& out, const set<T>& a) {
    out<<'{';
    for(const T &i: a) out<<i<<',';
    out<<'}';
    return out;
}
template<class T, class S>
ostream &operator <<(ostream& out, const map<T,S>& a) {
    out<<'{';
    for(auto &i: a) out<<i<<',';
    out<<'}';
    return out;
}

int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0}; // DRUL
const int INF = 1<<30;
const ll LLINF = 1LL<<60;
const ll MOD = 1000000007;

using R = long double; // Rにmint渡せるようにする
using P = complex<R>;
using L = pair<P,P>;
using G = vector<P>;
struct C {
    P c; R r;
    C() {}
    C(const P &a, const R &b) : c(a), r(b) {}
};
struct S : public L {
    S() {}
    S(const P &a, const P &b) : L(a,b) {}
};

const R EPS = 1e-8;
const R PI = atan(1)*4;

inline int sgn(const R& r) { return (r>EPS) - (r<-EPS); }
inline R dot(const P& a, const P& b) {
    return real(a)*real(b) + imag(a)*imag(b);
}
inline R det(const P& a, const P& b) {
    return real(a)*imag(b) - imag(a)*real(b);
}
inline P vec(const L& l) {return l.second - l.first;}
namespace std {
	bool operator < (const P& a, const P& b) {
		return sgn(real(a-b)) ? real(a-b) < 0 : sgn(imag(a-b)) < 0;
	}
	bool operator == (const P& a, const P& b) {
		return sgn(real(a-b)) == 0 && sgn(imag(a-b)) == 0;
	}
    bool cmp_y (const P& a, const P& b) {
        return sgn(imag(a-b)) ? imag(a-b) < 0 : sgn(real(a-b)) < 0;
    }
}

// P,L,Sについて入力
inline istream& operator>>(istream& is, P& p) {
    R x, y;
    is >> x >> y;
    p = P(x, y);
    return is;
}
inline istream& operator>>(istream& is, L& l) {
    P a, b;
    is >> a >> b;
    l = L(a, b);
    return is;
}
inline istream& operator>>(istream& is, S& s) {
    P a, b;
    is >> a >> b;
    s = S(a, b);
    return is;
}

// 線分abから見たcの位置
enum CCW{LEFT=1, RIGHT=2, BACK=4, FRONT=8, ON_SEG=16};
int ccw(P a, P b, P c) {
	P p = (c-a)/(b-a);
	if(sgn(imag(p)) > 0) return LEFT;
	if(sgn(imag(p)) < 0) return RIGHT;
	if(sgn(real(p)) < 0) return BACK;
	if(sgn(real(p)-1) > 0) return FRONT;
	return ON_SEG;
}

int intersect(const C& a, const C& b) {
	R dist = norm(a.c-b.c), r1 = (a.r+b.r)*(a.r+b.r), r2 = (a.r-b.r)*(a.r-b.r);
	if(sgn(r1-dist) < 0)  return 4;	// 円が離れている
	if(sgn(r1-dist) == 0) return 3;	// 外接
	if(sgn(r2-dist) < 0 && sgn(dist-r1) < 0) return 2; // 交差
	if(sgn(dist-r2) == 0) return 1; // 内接
	return 0;	// 内部に含む
}

// intersect=2 を確認すること
vector<P> crosspoint(C a, C b) {
    R d = abs(a.c-b.c), s = (a.r + b.r + d) / 2;
    R S = sqrt(s*(s-a.r)*(s-b.r)*(s-d)), h = 2*S/d;
    R m = sqrt(a.r*a.r - h*h);
    P p = (b.c - a.c) / abs(b.c - a.c);
    return {a.c + p*m + P(0,1)*h*p, a.c + p*m - P(0,1)*h*p};
}

signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    while(1) {
        ll n;
        cin >> n;
        if(!n) break;
        vector<R> x(n), y(n);
        vector<ll> v(n);
        REP(i, n) cin >> x[i] >> y[i] >> v[i];

        auto check = [&](R mid) {
            vector<C> cir(n);
            REP(i, n) cir[i].c = {x[i], y[i]}, cir[i].r = mid * v[i];
            vector<P> v;
            REP(i, n) v.push_back(cir[i].c);
            REP(i, n) FOR(j, i+1, n) {
                if(intersect(cir[i], cir[j]) != 2) continue;
                auto vp = crosspoint(cir[i], cir[j]);
                v.push_back(vp[0]);
                v.push_back(vp[1]);
            }
            for(P p: v) {
                bool flag = true;
                REP(i, n) {
                    if(sgn(abs(cir[i].c-p) - cir[i].r) > 0) {
                        flag = false;
                    }
                }
                if(flag) return true;
            }
            return false;
        };

        R lb = 0, ub = 200;
        REP(i, 50) {
            R mid = (lb+ub)/2;
            if(check(mid)) ub = mid;
            else lb = mid;
        }

        cout << fixed << setprecision(9) << ub << endl;
    }

    return 0;
}



Measured memory_bytes: 3448