Puzzle of the day · No. 2 · 14 October
There and back
At Schulz’s exchange booth a dollar is bought for 25,000 dong and sold for 25,500. Lucky changed 100 dollars into dong, thought better of it and changed all the dong straight back. How many dollars does he have now?
Answer: 98.04. For 100 dollars Lucky got 2,500,000 dong. On the way back a dollar costs 25,500, and 2,500,000 divides by that 98 times and a bit. The gap between buying and selling is the booth’s income: about two dollars per hundred for a single round trip.
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