**Counting on the time **
Suppose you start to prepare a meal at 9.30 a.m. and finish at 11.15 a.m.
a.m. means between midnight and noon, so 9.30 a.m. and 11.15 a.m. are both in the morning.
**How long did it take you to prepare the meal?**
You need to work out how many hours and minutes there are between half past nine in the morning and a quarter past eleven in the morning.
9.30 10.00 11.00 11.15
Counting on from 9.30, there are **30 minutes **until 10.00.
Between 10.00 and 11.00, there is **1 hour**.
Counting on from 11.00, there are **15** **minutes **until 11.15.
30 minutes + 1 hour + 15 minutes = 1 hour 45 minutes
So the meal took 1 hour and 45 minutes to prepare.
The answer is worked out by **counting on the time**.
**Counting on the time**
A disco starts at 9.30 p.m. and ends at 0.15 a.m.
9.30 p.m. is half past nine in the evening and 0.15 a.m. is a quarter past midnight.
**How long did the disco last?**
Counting on from 9.30, there are **30 minutes **to 10.00.
Counting on from 10.00, there are **2 hours** to midnight.
Counting on from midnight, there are **15 minutes** to 12.15.
**30 minutes + 2 hours + 15 minutes = **__2 hours 45 minutes__
So the disco lasted for 2 hours and 45 minutes.
Now try these. Show your working.
1 A sponsored swim event starts at 6.45 p.m. and ends at 9.20 p.m.
How long does the event last?
2 A team presentation starts at 11.30 a.m. and finishes at 1.45 p.m. How long does the presentation last?
**Counting on with the 24-hour clock**
Milly caught a train at Eastbourne at 06.50.
She arrived in the Lake District at 13.55.
How long was her journey?
**A**
06.50 and 13.45 are times in 24-hour clock.* *13.45 is the same as 1.45p.m. but you don’t need to use this fact to find the answer.
6 hours 55 minutes
**B **7 hours 5 minutes
**C **7 hours 15 minutes
**D **7 hours 55 minutes
Counting on from 06.50 to 07.00, there are **10 minutes**.
Between 07.00 and 13.00, there are **6 hours.**
Counting on from 13.00 to 13.55, there are** 55 minutes.**
**10 minutes + 6 hours + 55 minutes = **__7 hours 5 minutes__
**So the answer is **__B__.
Now try these. Show your working.
1 A First Aid course starts at 09.30 and finishes at 16.15.
How long does the course last?
2 A flight leaves Luton airport at 22.45 and arrives at its destination at 01.20. How long does the flight last?
**Subtracting the times directly **
Look what happens if you simply **subtract the 24-hour clock times. **
** 13.55**
** **__06.50__
** **__07.05__
This gives the answer without counting on in three stages.
**Now try these. Show your working and circle the correct answer.**
1 A video starts at ten past seven and finishes at five to nine.
How long did it last?
** A **1 hour 55 minutes
** B** 1 hour 45 minutes __ __
** C **2 hours 5 minutes __ __
**D** 2 hours 45 minutes
2 A coach leaves Leeds at 11.30 and arrives in London at 15.20.
How long was the journey?
** A **3 hour 10 minutes
** B** 3 hour 50 minutes __ __
** C **4 hours 10 minutes __ __
Question 2 is not so simple because you cannot work out 20 minus 30 without borrowing. Remember that 1 hour is worth 60 minutes.
**D** 4 hours 50 minutes
Num9
Page of
Mss1/L1.1
**Do'stlaringiz bilan baham:** |