The probability of choosing an orange Skittle on the first draw is 5/20, which simplifies to 1/4. Since the Skittle is replaced, the probability of choosing another orange Skittle on the second draw is also 1/4.
The probability of choosing a blue Skittle on the third draw is 3/20.
To find the probability of all three events occurring, we can multiply the probabilities together:
(1/4) x (1/4) x (3/20) = 3/160
Therefore, the probability of choosing an orange Skittle, replacing it, and then choosing a blue Skittle is 3/160.