Final answer:
The probability of selecting a slice of pepperoni pizza second given that a slice of cheese pizza was randomly selected first is 3/7.
Step-by-step explanation:
To find the probability of selecting a slice of pepperoni pizza second given that you randomly selected a slice of cheese pizza first, you need to determine the number of pepperoni pizza slices remaining after selecting a slice of cheese pizza first. Since there are four slices of pepperoni pizza and four slices of cheese pizza remaining, the total number of possible outcomes is 7 (4 pepperoni slices + 4 cheese slices - 1 already selected cheese slice). The number of favorable outcomes is 3 (3 remaining pepperoni slices). Therefore, the probability is 3/7.