The discussion revolves around the challenge of measuring 9 minutes using a 4-minute hourglass and a 7-minute hourglass. Participants explore various methods and strategies to achieve this measurement, focusing on the mechanics of timing and flipping the hourglasses.
Participants express differing views on the efficiency of the proposed methods, with some suggesting that certain approaches waste time while others hint at more optimal solutions. The discussion remains unresolved regarding the best method to measure 9 minutes.
Some participants' claims depend on the precise timing of flips and the interpretation of efficiency, which may not be fully articulated. There are also unresolved steps in the proposed methods that could affect the outcome.
Alexmahone said:Bob owns a couple of hourglasses -- one is a 4 minute hourglass and the other is a 7 minute hourglass. If Bob wants to measure 9 minutes, how could he do it?
CaptainBlack said:Start then together, turn the 4 when it is emply.
When the 7 is empty turn the 4.
At this point it has 1 minute to go...
Alexmahone said:Now there are 3 minutes remaining in the 7.
When the 7 is empty there is 1 minute remaining in the 4. So why would you want to turn it?
CaptainBlack said:Start then together, turn the 4 when it is emply. When the 7 is empty start timing the nine minutes, at this point the four minute glass has 1 minute to go. When empty turn it, 5 minutes have elapsed. Turn it again, and when empty 9 minutes have elapled.
CB
Alexmahone said:Hint: There is a solution that wastes no time and measures 9 minutes in one go.