The Science Club Announcement: Start Time and Two Constraints
You are a first-year student at a Toyama public high school. At lunch, you hear this announcement from the science club president over the school speakers: 'The science club meets today. We will not use Room 203 because the second-year students are preparing a presentation there. Come to the library on the second floor instead. The library closes at 4:40, and the librarian has asked us to finish by 4:25. The meeting will start 15 minutes later than usual. The usual start time is 3:50. Bring your experiment notebooks. Leave your glass slides at home; we will not use microscopes today. If you cannot attend, send me a message by 3:30. Do not send it after 3:30.' A classmate tells you she will arrive at 4:10 and leave at 4:35. Another classmate says he will bring slides because 'better safe than sorry.'
1. At what time does the science club meeting start? Show how you use two different numbers from the announcement to get your answer.
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The meeting starts at 4:05 p.m.
The announcement gives the usual start as 3:50 and says the meeting will start '15 minutes later than usual.' 3:50 + 15 minutes = 4:05.
A common mistake is to use 4:25 (the librarian's finish time) or 4:40 (library closing time) as the start. Neither is a start time; they are end constraints. The reasoning must connect the 'usual start' number to the 'later than usual' number, not just pick any number from the announcement.
2. A classmate plans to arrive at 4:10 and leave at 4:35. Identify two separate problems with this plan, using the announcement.
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Problem 1: She arrives after the start. The meeting starts at 4:05, so arriving at 4:10 means she misses the first five minutes.
Problem 2: She plans to leave after the librarian's deadline. The librarian asked the club to finish by 4:25. Leaving at 4:35 breaks that request, and it is only five minutes before the library closes at 4:40.
A third issue is not a problem with her plan but with the message rule: because she plans to attend, she does not need to send a 3:30 message; if she later cannot attend, the deadline has passed. The two direct problems are lateness and overstaying.
3. The classmate who brings glass slides says, 'Better safe than sorry.' Using the announcement, explain why this reasoning does not apply here.
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'Better safe than sorry' fits when the risk is uncertain-if you do not know whether slides are needed, bringing them could help. Here the announcement removes the uncertainty: it says 'we will not use microscopes today' and directly tells students to 'leave your glass slides at home.'
Bringing them is not extra safety; it disobeys a clear instruction and adds something unnecessary to carry. The correct action is to follow the specific instruction, not to prepare for a situation the speaker has already ruled out.