Brain-Teaser 473

From The Sunday Times, 21st June 1970 [link]

The conical glasses at the Hôtel d’Or hold one eighth of a litre and are embellished from base to brim with a picture of Bacchus. In making the hotel’s famous Gouttes d’Or, sold at NF 5.20, it was customary to fill the glass up to Bacchus’ neck (4/5th of the way up the glass) and then add an olive; the profit on raw materials was a modest 100 per cent.

Gaston, the barman, has decided that he must make the more realistic profit of 400 per cent. So now the olive is put in first and then liquor is added up to the level of Bacchus’ chest (3/5ths of the way up the glass). The price has been reduced to NF 4.80.

Gaston explained: “Ze olives are standard sized and cost me one centime a cc. Yes, I could put in ze olive after measuring out the liquid — but zen it would be necessary to charge …”

How much?

This is a corrected version of the originally published puzzle. In the original version the price of the first glass was incorrectly given as NF 5.30 (instead of NF 5.20). The puzzle can still be solved in the same way, but the numbers don’t work out as nicely.