//非(常规)二分,含有精度,估算高度而不是去计算高度
//使用到eps的l,r不需要+1-1
#include<iostream>
#include<math.h>
using namespace std;
#define PI acos(-1)
double r, R, H, V, v2, r1;
bool check(double h) {
	r1 = (h / H) * (R - r) + r;
	v2 = (1.0 / 3.0) * PI * h * (r1 * r1 + r * r1 + r * r);
	return v2 <= V;
}
int main() {
	int t;
	scanf("%d", &t);
	while (t--) {
		scanf("%lf%lf%lf%lf", &r, &R, &H, &V);
		double l = 0, r = 100, mid;
		while (r - l > 1e-7) {
			mid = (l + r) / 2;
			if (check(mid)) l=mid;
			else r=mid;
		}
		printf("%.6lf", r);
	}
	return 0;
}