Time (Copy)
Practice Questions — 1.15 Time
Question 1
Convert the following into seconds:
(a) 8 minutes
(b) 2 hours 15 minutes
(c) 1 day
Question 2
Express the following times using the 24-hour clock:
(a) 6:45 a.m.
(b) 12:20 p.m.
(c) 9:15 p.m.
Question 3
Express the following times using the 12-hour clock with a.m./p.m.:
(a) 1510
(b) 0045
(c) 2315
Question 4
A train leaves Karachi at 0940 and arrives in Lahore at 1635.
How long does the journey take? Give your answer in hours and minutes.
Question 5
An exam starts at 10:30 a.m. and lasts 2 hours 45 minutes.
At what time does the exam end, in both 12-hour and 24-hour clock notation?
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
Question 6
A bus departs at 2225 and arrives at 0140 the next day.
Find the journey time in hours and minutes.
Question 7
If it is 8:15 a.m. in London (GMT), what is the local time in Karachi (GMT+5)?
Question 8
A person works 5 hours 45 minutes on Monday, 6 hours 20 minutes on Tuesday, and 7 hours 15 minutes on Wednesday.
Find the total time worked over the three days.
Question 9
Convert:
(a) 2.5 hours into hours and minutes
(b) 3.75 hours into hours and minutes
(c) 1.2 days into hours
Question 10
A plane leaves New York at 2015 local time. The flight takes 11 hours 30 minutes.
(a) What will be the arrival time in New York local time?
(b) If London is 5 hours ahead, what will be the arrival time in London?
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
Answer key and explanations — 1.15 Time
1.
(a) 8 min = 8 × 60 = 480 s
(b) 2 h 15 min = (2 × 3600) + (15 × 60) = 7200 + 900 = 8100 s
(c) 1 day = 24 × 3600 = 86 400 s
Explanation: 1 min = 60 s, 1 h = 3600 s, 1 day = 24 h.
2.
(a) 6:45 a.m. → 0645
(b) 12:20 p.m. → 1220
(c) 9:15 p.m. → 2115
Explanation: In the 24-hour clock, add 12 hours to p.m. times except 12 p.m.
3.
(a) 1510 → 3:10 p.m.
(b) 0045 → 12:45 a.m.
(c) 2315 → 11:15 p.m.
Explanation: Convert hours above 12 by subtracting 12 and adding p.m.
4.
From 0940 to 1635 = 6 h 55 min
Answer: 6 hours 55 minutes
Explanation: Subtract times carefully (1635 − 0940).
5.
Start = 10:30 a.m. + 2 h 45 min = 1:15 p.m.
24-hour clock = 1315
Explanation: Add duration to start time, convert to both notations.
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course
6.
2225 → 0140 next day
From 2225 to midnight = 1 h 35 min
From 0000 to 0140 = 1 h 40 min
Total = 3 h 15 min
7.
London = 8:15 a.m. (GMT)
Karachi = GMT+5 → add 5 h → 1:15 p.m.
8.
Monday = 5 h 45 min
Tuesday = 6 h 20 min
Wednesday = 7 h 15 min
Total = (5+6+7) h + (45+20+15) min = 18 h + 80 min = 19 h 20 min
9.
(a) 2.5 h = 2 h + 0.5 × 60 = 2 h 30 min
(b) 3.75 h = 3 h + 0.75 × 60 = 3 h 45 min
(c) 1.2 days = 1.2 × 24 = 28.8 h = 28 h 48 min
10.
Departure = 2015, flight = 11 h 30 min
(a) Arrival (New York time) = 2015 + 11 h 30 min = 0730 next day
(b) London = New York + 5 h = 1230 next day
Written and Compiled By Sir Hunain Zia, World Record Holder With 154 Total A Grades, 7 Distinctions and 11 World Records For Educate A Change O Level And IGCSE Mathematics Full Scale Course