The Library Poster and the Missing Opening Time
A Grade 5 class visits a small town library. Near the entrance hangs a poster headed "Summer Opening Hours." It lists Monday to Thursday 9:00–17:00, Friday 9:00–19:00, Saturday 10:00–16:00, and a final line: "Closed Sundays and public holidays." Below the table, in smaller print, a note says: "During the last two weeks of August the library closes at 15:00 on weekdays. Weekend hours do not change." A pupil, Mira, wants to return three books on Saturday 23 August at 16:30. She also plans to come on Friday 29 August at 18:00 to use a computer. The librarian mentions that 25 August is a public holiday. Mira says, "The poster says Friday is open until 19:00, so I can come at 18:00 on the 29th."
1. Using only the poster, decide whether Mira can return her books on Saturday 23 August at 16:30. Explain which lines of the poster you used and which you ignored, and why.
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No, she cannot. The main table says Saturday hours are 10:00–16:00, so 16:30 is after closing. The small-print note about the last two weeks of August says weekend hours do not change, so the early 15:00 closing does not apply to Saturday and does not extend it either. The Sunday/holiday line is irrelevant here because 23 August is a Saturday, not a Sunday or a stated public holiday. A careful reader must combine the table with the note: the note changes only weekday closing times, so Saturday remains 10:00–16:00. Mira would need to arrive by 16:00 or choose another day.
2. Mira claims she can use a computer on Friday 29 August at 18:00. Is her reasoning sound? Identify the exact part of the poster that affects her claim.
Read the worked answer
Her reasoning is not sound. She quotes the main table (Friday 9:00–19:00) but overlooks the small-print note: during the last two weeks of August, weekday closing is 15:00. Friday 29 August falls in that period, and Friday is a weekday, so the library closes at 15:00, not 19:00. The note overrides the table for weekdays in late August. The public holiday on 25 August is a separate fact and does not affect 29 August. The correct conclusion is that 18:00 on 29 August is well after closing; she should come before 15:00.