import sys

sys.setrecursionlimit(10**5 + 10)

INF = float("inf")


def solve():
    N, M, K = [int(s) for s in input().split()]

    remain = (N * M) - K

    # comb(m - 2, rem - 1) / comb(m - 1, rem)
    # n!*(r-1)!/r!(n-1)!
    P = remain / (M - 1) if remain < (M - 1) else 1.0

    cache = [INF] * (N)

    def dp(n):
        if cache[n] != INF:
            return cache[n]

        if (N - 1 - n) * M >= K:
            cache[n] = 1.0
            return cache[n]

        if n == 0:
            cache[n] = (1 / M) * P
            return cache[n]

        p = (M - 1) / (M * (n + 1)) * P
        p += n / (n + 1) * dp(n - 1)

        cache[n] = p
        return cache[n]

    print(dp(N - 1))


if __name__ == "__main__":
    T = int(input())

    for _ in range(T):
        solve()