Wei Lin's school assembly starts at 7.30 a.m. Every morning he needs 15 minutes to get ready at home, 10 minutes to walk to the MRT station, and 35 minutes for the train journey to school. What is the LATEST time he must wake up so that he reaches school exactly when the assembly starts?
Show Worked Solution
Worked Solution
Step 1: Find the total time Wei Lin needs before assembly starts.
Get-ready: 15 min
Walk to MRT: 10 min
Train journey: 35 min
Total = 15 + 10 + 35 = 60 min = 1 hour
Step 2: Work backwards from the assembly start time of 7.30 a.m.
Step 3: 7.30 a.m. − 1 hour = 6.30 a.m.
Step 4: Check forward: 6.30 + 15 min = 6.45; 6.45 + 10 min = 6.55; 6.55 + 35 min = 7.30 a.m. ✓
Final: He must wake up by 6.30 a.m.
Answer: 6.30 a.m.
Correct answer: 6.30 a.m.
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