The probability of selecting a white ball is 5/12 and a black ball 7/12.
(1) The probability of selecting another white ball when the first is replaced is (5/12)2, and then, after replacing the second ball, selecting a third white ball is (5/12)3=125/1728 (7.23% approx).
For three black balls similarly selected and replaced the probability is 343/1728 (19.85% approx).
(2) If the balls are not replaced, the white ball selection probability is (5/12)(4/11)(3/10)=1/22 (4.56% approx).
Similarly, for the black balls the probability is (7/12)(6/11)(5/10)=7/44 (15.91% approx).