from decimal import Decimal

T = int(input())
for _ in range(T):
    N, M, K = map(str, input().split())
    dn = Decimal(N)
    dm = Decimal(M)
    dk = Decimal(K)
    if int(K) <= int(M) * (int(N) - 1):
        dl = Decimal(str((int(K) + int(M) - 1) // int(M)))
        print(Decimal('1.0') - dl / (dn * dm))
    else:
        print((dm * dn - dk) / dm)