I want to check if my answer makes sense.

question:

You are standing in line. Think about what you would be doing if you are not in this line. The alternatives are infinite and computing the cost of them all is impossible. However, since you could only be doing one thing (not all of them) if you are not in this line, determining the opportunity cost requires only knowing the one thing you would be doing. Calculate (in $$$)

Answer:

Supposed if I were waiting in line to buy toilet papers, but it would take me one hour to enter the store because the line is long, and one pack of toilet paper will cost $15. If not standing in line, the other option for this time is to stay home and work on my work project. My job pays me to work at home due to COVID-19, and I get paid $25 per hour.

Thus, stand in line will is $25(2) +$15 for a pack toilet paper.

The opportunity cost for me to stay in line is $65 for 2 hours in and bought one pack of toilet paper.

What if I use a different time, instead of waiting in line during my work hour, to go to the store at night when people are sleeping? It would cost less than waiting in line during the day.