50人参加考试,48人及格,及格人数与不及格人数的比是 ,及格率是 .
9: ==3÷5.
3÷4==27: = (填小数)= %.
÷4==0.25= :8.
=9÷ = :8== (填小数)
3: ==15÷ = ×= (小数).