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'Night Watchmen' printed from https://nrich.maths.org/
Answer: 12 noon (assuming 12 hour analogue watches. 24 hour watches won't agree again until midnight tomorrow, when they will both say midday)
Time |
Granny |
Grandpa |
Difference |
00:00 |
00:00 |
00:00 |
0 |
01:00 |
01:30 |
00:30 |
1 |
02:00 |
03:00 |
01:00 |
2 |
03:00 |
04:30 |
01:30 |
3 |
+1 hour apart each hour
12 hours apart after 12 hours
They say the same time at 12 noon (6 o'clock)