The Book Swap Ticket Cap
Keisuke reads a notice titled 'Book Swap Day' at his school library: 'Bring up to three books in good condition. For each book you bring, you receive one ticket. Use one ticket to take home any one book. Textbooks and dictionaries cannot be swapped. Comics and novels are welcome. Tickets cannot be exchanged for money.' Keisuke has four novels he wants to swap. He brings all four and asks for four tickets. The librarian says, 'Read the notice again.' Keisuke's friend says he can get four tickets because he brought four books. Another friend says he can bring only three books but can still take three books. Keisuke also wants a dictionary on the swap table. The librarian points to the words 'up to' and waits.
1. How many tickets should Keisuke receive, and can he take the dictionary? Justify using only the notice.
Read the worked answer
Keisuke should receive three tickets, not four. The notice says 'Bring up to three books' and 'For each book you bring, you receive one ticket.' The cap on bringing limits the number of eligible books to three, so the fourth novel cannot earn a ticket. The phrase 'up to' sets a maximum, and 'for each' does not override that maximum. With three tickets he may take home three swap books. He cannot take the dictionary: the notice says 'Textbooks and dictionaries cannot be swapped,' and that exclusion is stated separately from the ticket rule. The dictionary is visible on the table, but visibility does not make it eligible. The librarian's 'Read the notice again' is a hint to check both the cap and the exclusion.
2. A friend claims 'He can bring only three books but can still take three books.' Is that consistent with the notice? Explain the difference between bringing and taking.
Read the worked answer
The friend's claim is half right and half misleading. If Keisuke brings three eligible novels, he receives three tickets and can take home three swap books, so 'bring only three but take three' is consistent with the notice. But if he brings four, he still receives only three tickets, so the fourth book gives him no extra taking power. The notice distinguishes bringing (contributing books, capped at three) from taking home (using tickets, one per eligible brought book). Keisuke should leave the fourth novel at home or donate it only if the library has a separate donation box; the swap notice does not promise anything for a fourth book.