Each of the nine digits 1, 2, 3, 4, 5, 6, 7, 8, and 9 is marked on a separate slip of paper and the nine slips are placed in a box. Three slips of paper will be randomly selected with replacement, and in the order selected the digits will be used to form a 3-digit number.
Quantity A
The probability that the 3-digit number will be greater than 600
Quantity B
$$\frac{4}{9}$$