The master, having 10 parts, of which 3 are non-standard, checks the parts one by one until he comes across a standard one

The master, having 10 parts, of which 3 are non-standard, checks the parts one by one until he comes across a standard one. What is the likelihood that he will check exactly two details?

Obviously, the probability of the A1 event is = 3/10, in addition, P = 7/9, since before taking the second part, the master had 9 parts left, of which only 2 are non-standard and 7 are standard. By the multiplication theorem
P = 3/10 * 7/9 = 7/30