Answer:
The expected revenue is $984.6.
Explanation:
The tourist operator sells 21 non-refundable tickets, as the tourist may not show up.
The tourist have a probability of 0.02 of not showing up, independent of each other.
The income is the selling of the 21 tickets at $50 each.

The only cost considered in this problem is the refund if a tourist show up and a seat is not available.
This only happens when the 21 tourists show up. If each tourist has a probability of 0.02 of not showing up, they have a probability of 0.98 of showing up.
For the event that the 21 tourists show up, we have the probability:

For each of this event, the tour operator has to pay $100, so the expected revenue of the tour operator is:
