Chapter 12, Racing Seconds, covers converting between minutes and seconds, and reading and converting between 12-hour (am/pm) and 24-hour clock time. These questions use race-timing situations to practise both skills.
Practice Questions
Q1. How many seconds are there in 3 minutes?
3 × 60 = 180 seconds.
Q2. A runner finishes a race in 125 seconds. Express this in minutes and seconds.
125 seconds = 120 seconds + 5 seconds = 2 minutes 5 seconds.
Q3. Convert 4:30 pm to 24-hour clock format.
4:30 pm = 16:30.
Q4. Convert 21:15 (24-hour time) to 12-hour clock format.
21:15 = 9:15 pm.
Q5. Two racers finish at 45 seconds and 1 minute 5 seconds. Who is faster, and by how much?
1 minute 5 seconds = 65 seconds; 65 − 45 = 20 seconds, so the racer who finished in 45 seconds is faster by 20 seconds.
Why These Help
Reading race timers, train and flight schedules, and digital clocks all depend on comfortably switching between seconds, minutes and the two common ways of writing the time of day.
Frequently Asked Questions
Q. Why do we sometimes use 24-hour time instead of am/pm?
It avoids confusion between morning and evening, since every hour of the day gets one unique number — which is why timetables for trains and flights usually use it.
See the Chapter 12 Solutions and Revision Notes for the full walkthrough.
