Sand Timers

puzzle:- sand timers

You have two sand timers, which can show 4 minutes and 7 minutes respectively. Use both the sand timers(at a time or one after other or any other combination) and measure a time of 9 minutes.

how can you measure 9 minutes ?

Answer:-

Here is the explanation 

1. Start the 7 minute sand timer and the 4 minute sand timer.
2. Once the 4 minute sand timer ends turn it upside down instantly.
3. Once the 7 minute sand timer ends turn it upside down instantly.
4. After the 4 minute sand timer ends turn the 7 minute sand timer upside down(it has now minute of sand in it)

So effectively 8 + 1 = 9

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