# Maths Topic 30 - Time: Durations, 24hour clock, timetables

Time: durations, 24hour clock, timetables is commonly tested in 11+ and Selective School exams in the UK.

## Examples

### Example Question 1:

1) What are these times in 24-hour time?

(a) 6:15pm,  (b) 5:00pm  (c) 10:55pm,  (d) 7:30am,  (e) 12:05am

2) What are these times in 12-hour time, using am and pm?

(a) 16:12,  (b) 23:55,  (c) 01:25,  (d) 20:03,  (e) 10:20

1) (a) 18:15,  (b) 17:00,  (c) 22:55,  (d) 07:30,  (e) 12:05

2) (a) 4:12pm,  (b) 11:55pm,  (c) 1:25am,  (d) 8:03pm,  (e) 10:20am

Explanations:

1) For pm times add 12 hours to change times into the 24-hour clock.

(2) For times greater that 13:00 subtract 12 hours to change times into the 12-hour clock

### Example Question 2:

a)  On Monday she arrives at 09:04. What time does school start if she is 24 minutes late?

b) On Wednesday she stays for netball practice starting at 15:45, which is one hour and 20 minutes long. If it takes her 22 minutes to walk home afterwards what time will she arrive?

a) 08:45

b) 17:27

Explanations:

a) 09:04 subtract 24 minutes = 08:45

b) Netball practice will finish at 17:05 (15:45 + one hour and 20 minutes). Add the time to walk home to this total 17:05 + 22 minutes = 17:27