You have 13 air conditioners, 4 are defective (stat problem)

In a shipment of 13 room air conditioners, there are 4 with defective thermostats. Two air conditioners will be selected at random and inspected one after another. Find the exact probability that:

1. P(The second air conditioner is defective) = ?
2. P (Exactly one is defective) = ?

q1
P[2nd bad] = P[good-bad] + P[bad-bad] = 9/13 *4/12 + 4/13 *3/12 = 4/13 <------

q2
P[exactly 1 bad] = P[bad-good] + P[good-bad] = 4/13 *9/12 + 9/13 *4/12 = 6/13 <------