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On a recent trip to a restaurant, we entered the restaurant at 2:15 P.M. were escorted to a table and presented with a menu which said, "Saturday Luncheon Menu." Apparently dinner begins at 4:00 PM at this restaurant.

Thinking that the prices were lower than I had remembered for past dinners, I requested a Saturday dinner menu and compared some prices with the following result. The luncheon menu had prices for Sauerbraten, Weiner Schnitzel, and Johannisberg Riesling by the glass with the following prices respectively $11.75, $12.50, and 5.25. The dinner menu had the same items for $13.95, $14.95 and $6.00 respectively.

Assume that you are told that the entire difference in prices is related to higher costs during the dinner period. In a sentence or two, how might you explain the higher costs?