Final answer:
The opportunity cost of bus tickets stays the same when both the price of bus tickets and burgers double because the ratio between their prices remains constant. Alphonso's budget constraint is affected by his increased budget and the price changes, and the overall impact depends on the interplay of these changes.
Step-by-step explanation:
The opportunity cost of bus tickets is a concept in economics that describes what is foregone in order to acquire something else. Originally, when the price of bus tickets was $0.50, and burgers were $2, the opportunity cost of a bus ticket was 0.25 burgers because one could buy four tickets for the price of one burger. However, when the price of bus tickets doubles to $1, and the price of burgers also doubles to $4, the opportunity cost of bus tickets remains the same (0.50/4 = 0.25). This is because the ratio of the price of bus tickets to burgers remains constant despite the price changes.
The weekly budget increase from $10 to $20 in Alphonso's case affects his budget constraint because he now has more money to spend, which typically shifts the budget constraint outwards, allowing him to potentially consume more of both goods. However, due to the simultaneous increase in the price of both goods, the overall effect on the budget constraint will depend on how these changes interact with each other.