- At 0 minutes: Start both hourglasses at the same time.
- At 4 minutes: 4 minutes hourglass runs out and flip it. 7 minutes hourglass is left with 3 minutes.
- At 7 minutes: 4 minutes hourglass is left with 1 minute. 7 minutes hourglass runs out and flip it.
- At 8 minutes: 4 minutes hourglass runs out and 7 is filled with 6 minutes and 1 minute on the other side. Flip it as the sand is left with 1 minute.
- At 9 minutes: 7 minutes hourglass becomes empty from above side.
Hence we measured 9 minutes.
This article is contributed by Vikash Kumar. Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
My Personal Notes arrow_drop_up
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