You select a family with four children. If M represents a male child and F a female child, the set of equally likely outcomes for the children's genders is {FFFF, FFFM, FFMF, FMFF, MFFF, MFFM, MFMF, MMFF, FFMM, FMFM, FMMF, FMMM, MFMM, MMFM, MMMF, MMMM). Find the probability of selecting a family with exactly four female children. The probability of having exactly four female children is (Type an integer or a simplified fraction.)