5. (10%) The probabilities of two independent events A and B: \( \mathrm{P(A)} = 0.2 \), \( \mathrm{P(B)} = 0.5 \). Please calculate \( \mathrm{P(A^c \cap B^c)} \). \( \mathrm{A^c} \) and \( \mathrm{B^c} \) represent the complement of A and B.