Answer: Our required probability is 0.4.
Step-by-step explanation:
Since we have given that
Number of window seats = 12
Number of aisle seats = 8
Total number of seats = 12+8 = 20
According to question, the next person to buy a ticket will be assigned to one of those seats.
Probability that the next person will be assigned to an aisle seat is given by

Hence, our required probability is 0.4.