Chork's Puzzle 19
Difficulty Rating: 5
Jon set off from his home to his office on his brand new car, driving at a constant speed of 66km/h. After driving for 16km, Jon realises that he left an important document at home and checks his watch to see if he has enough time to drive back home to collect the document. When he glanced at his watch, the minute hand was exactly over the hour hand.
Assuming at the time Jon set off, it was a whole number of minutes (ie. it just reached a particular minute and not halfway into the minute),
Jon set off from his home to his office on his brand new car, driving at a constant speed of 66km/h. After driving for 16km, Jon realises that he left an important document at home and checks his watch to see if he has enough time to drive back home to collect the document. When he glanced at his watch, the minute hand was exactly over the hour hand.
Assuming at the time Jon set off, it was a whole number of minutes (ie. it just reached a particular minute and not halfway into the minute),
What time did Jon set off?
If you know the answer, post it in the comments section of this post.
If you know the answer, post it in the comments section of this post.
posted by chorkie @ 3:27 PM
2 Comments:
At Saturday, July 01, 2006 10:56:00 PM,
woonie said…
1040h
Times when hour and minute hand coincide:
0 12:00:00.00
1 01:05:27.27
2 02:10:54.54
3 03:16:21.81
4 04:21:49.09
5 05:27:16.36
6 06:32:43.63
7 07:38:10.90
8 08:43:38.18
9 09:49:05.45
10 10:54:32.72
[16km / 66(km/h)]*60
= 160/11 mins
= 14mins + 6/11min
= 14mins 32.72secs
So the only time when the fraction of a second is .72 and the hour hand and second hand coincide is at 10:54:32.72am/pm.
so you take away 14mins 32.72secs and u see that Jon set off at 1040h. =))
Source: Yahoo! Answers
At Monday, March 05, 2007 9:19:00 AM,
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