Unit 9
Speed and Time Calculation
About this unit
Tackle multi-step time problems involving international travel, time zone conversions, layover times, relative speed, and scheduling windows. Questions present realistic scenarios requiring careful arithmetic with hours, minutes, and time zone offsets.
What types of questions will you face?
- 1Calculate departure or arrival time for a flight involving time zone differences and known flight duration
- 2Multi-leg flight: add flight time + layover, then apply time zone offset to find local arrival time
- 3Find when two people in different time zones can both be free at the same time
- 4Relative speed: an express train travels N times as fast as a slow train — find its departure time
- 5Multi-stage journey (walk + bus + train): calculate the latest possible departure time to arrive by a deadline
- 6Clock angle calculation: find the angle between clock hands at a given time
Skills you will build
- Converting between time zones by adding or subtracting the offset correctly
- Tracking time across day boundaries (e.g. departing at 11:30 PM Thursday, arriving Friday)
- Adding and subtracting hours and minutes accurately
- Using relative speed relationships (twice as fast = half the time)
- Working backwards from a deadline to calculate the latest valid start time
By the end of this unit, you will be able to
- Solve any multi-leg international flight problem with time zone changes
- Find valid meeting windows for people in different time zones
- Calculate the minimum time needed for a multi-stage journey
- Handle relative speed problems with confidence using the speed-time relationship
Difficulty profile
Medium difficulty (avg 3.00). Single time-zone problems are Easy; multi-leg flights crossing multiple time zones are Difficult. The clock angle question is an unusual harder variant.
Exam tip: Speed and Time Calculation
Draw a timeline. Write departure time, add flight duration, then apply the time zone offset at the end. Always note whether the destination is ahead (+) or behind (-) the origin, and watch for midnight crossings.
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