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# Mouldy Test Tube

3 replies to this topic

### #1 normdeplume

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Posted 20 June 2007 - 10:06 AM

As an experiment in a school lab, a pupil began to grow a mould sample. He observed it for a full month Moday to Friday and it went un-observed on the weekends. He noted that the mould doubled in size every day.

The experiemnt began on Wednesday May, 1 and by Friday May 31 the experiment ended with as mentioned the test-tube being full.

His teacher asked him if he could give an exact date of when the test tube was half full, bearing in mind there were 2 days every week that he did not see the experiment, would he be able to say when the tube was half full? and what date would that be?
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### #2 rockypg

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Posted 20 June 2007 - 01:10 PM

err.. Whats with all the unnecessary and confusing details?

you have noted in the beginning of the puzzle that "He noted that the mould doubled in size every day". Assuming this is true, we need no other information other than the day on which the test tube was full, to predict the day the test tube was half-full.

The very day before the test tube was full, it was half-full.

BTW this puzzle is very similar to this one
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### #3 comperr

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Posted 20 June 2007 - 02:15 PM

The day before it was full. Very cute with the extraneous details.
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### #4 normdeplume

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Posted 20 June 2007 - 02:55 PM

Comperr picked up on the fact I included a lot of extenuous detail as a blind to try to make a very simple puzzle seem more dificult.

To all intents and purposes, it is identical to the puzzle rockypg points to, but I hadn't seen that one on this site.
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