Mdm Lily Hoi Fast clocks Jacks clock was 20 minutes fast He saw that the time was 10 10 What was the actual time Since his clock is fast it has gained 20 minutes We need to let it ID: 750697
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Slide1
Slow and Fast Clocks
By
Mdm
Lily HoiSlide2
Fast clocks
Jack’s clock was 20 minutes
fast
. He saw that the time was 10 10.What was the actual time?
Since his clock is fast, it has “
gained” 20 minutes.We need to let it “lose” 20 minutes to get the actual time.
Actual time:
09 50Slide3
Slow clocks
Jack’s clock was 20 minutes
slow
. He saw that the time was 10 10.What was the actual time that Jack woke up?
Since his clock is slow, it has “
lost” 20 minutes.We need to let it “gain back” 20 minutes to get the actual time.
Actual time:
10 30Slide4
Try it!
Jack’s clock is 20 minutes slow. He woke up one day and saw that the time was 08 55. What was the actual time?
Since his clock is slow, it has “
lost
” 20 minutes.
We need to let it “gain back” 20 minutes to get the actual time.
Actual time:
09 15Slide5
Try it!
William’s clock is 30 minutes fast. He woke up one day and saw that the time was 07 20. What was the actual time that William woke up?
Since his clock is fast, it has “
gained
” 30 minutes.We need to let it “
lose” 30 minutes to get the actual time.Actual time: 06 50Slide6
Challenge yourself!
Clara sets her watch correctly at noon. For every actual hour, the watch loses exactly 15 minutes. It now shows 15 00. What should be the correct time now?
Since her watch “
loses
” 15 minutes at every hour, her watch is “
slow”.We need to let it “gain” 15 minutes at every hour to get the actual time. Slide7
Challenge yourself!
Clara sets her watch correctly at noon. For every actual hour, the watch loses exactly 15 minutes. It now shows 15 00. What should be the correct time now?
Total lost: 1 hour (15 min x 4)
Actual time:
16 00
Clock
Actual
Noon
Noon
12
45
13 00
13 30
14 00
14 15
15 00
15 00
16 00Slide8
Challenge yourself!
Raymond sets his clock correctly at midnight. For every actual hour, the clock gains exactly 20 minutes. It now shows 05 20. What should be the correct time now?
Since his clock “
gains
” 20 minutes at every hour, h
is clock is “fast”.We need to let it “lose” 20 minutes at every hour to get the actual time. Slide9
Challenge yourself!
Raymond sets his clock correctly at midnight. For every actual hour, the clock gains exactly 20 minutes. It now shows 05 20. What should be the correct time now?
Total gain: 1 h 20 min (20 min x 4)
Actual time:
04 00
Clock
Actual
Midnight
Midnight
01
20
01
00
02
40
02
00
04
00
03
00
05
20
04
00Slide10
Challenge yourself!
When it was 13 20 in Singapore, it was 07 20 in Amsterdam.
At 05 45 on Tuesday in Singapore, Mr Lee made a call to Amsterdam.
What time and day would it be in Amsterdam?
Between Sg and Amst -> 6 h difference
Time in Amst is slower than Sg. It is 6 h behind Sg time.Time in Sg is faster than Amst.
23 45 00 45 05 45
Mon Tues
Tues
Ans
:
23 45 on Monday in Amsterdam
1h 5h