The Bus Timetable Decision
A student must reach a TAFE campus by 9:00 am for an exam. The bus timetable shows: Route 12 leaves the interchange at 7:40, 8:10 and 8:40, taking 25 minutes to the campus. Route 7 leaves at 7:35 and 8:05 and takes 40 minutes. The student must also walk 10 minutes from home to the interchange and 5 minutes from the bus stop to the exam room.
The exam rules say students must arrive at least 15 minutes before the start.
1. Which bus should the student catch to arrive on time with the least waiting?
Read the worked answer
Work backwards from the 9:00 am start. The student must be in the exam room by 8:45 am (15 minutes early).
Route 12, 8:10 bus: arrives campus 8:35, plus 5-minute walk = 8:40 in the room. That is 20 minutes early - fine.
Route 12, 8:40 bus: arrives 9:05 - too late.
Route 7, 8:05 bus: arrives 8:45, plus 5-minute walk = 8:50 - too late for the 8:45 rule.
Answer: Catch the Route 12 bus at 8:10 am. It arrives at 8:40 in the room, comfortably before 8:45.
2. What time must the student leave home to catch that bus?
Read the worked answer
The chosen bus is Route 12 at 8:10 am. The walk to the interchange takes 10 minutes.
8:10 minus 10 minutes = 8:00 am. Leaving exactly at 8:00 gives no margin for delay.
Answer: Leave home by 8:00 am at the latest, but leaving around 7:50 am gives a safety buffer in case the walk is slower.