from math import floor
for _ in range(int(input())):
    t, m, l = map(float, input().split())
    ok = 0; ng = 5101
    for _ in range(100):
        mid = (ok+ng)/2
        v = mid/3.6
        if v*t+v*v/20/m < l: ok = mid
        else: ng = mid
    print(f"{floor(mid*100)/100:.2f}")