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Monday Madness

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A family has a mining claim. The claim actually belongs to the father, but the two brothers are now working it. The agreement is that they give their father a minimum of 10% (rounded up to the next full ounce) of each seasons take - and the two brothers split the remainder.

This year, they have collected 1.5 lbs of gold dust. They have a balance scale and a 5 ounce weight to work with.

What is the least amount of weighings that will be required to split the profits correctly?
Please explain your answer.
ok i think it would be 8 if they already knew they had 24 oz of dust, if they didn't then it's going to be a lot more. the dad needs 3 oz for his 10% rounded up. 4 weighings with the 5oz weight makes them have 5 piles of gold, 5, 5, 5, 5, 4 now they put the 4 oz pile on one side of the scales and a 5 oz pile on the other then take gold from the 5oz side until they balance meaning that was 1 oz of gold they removed, they put that to one side for dad and repeat the process with another 2 piles of 5oz so they now have dad's 3 ozs of gold and 5 piles of gold 4, 4, 4, 4, 5. so far that's 7 weighings and the last 1 is to split the 5oz pile 50/50. now they each have 2 piles of 4 oz gold and a pile of 2.5oz gold. :popcorn: just had a thought are we dealing with lbs and ozs or troy lbs and ozs? because there's only 12 troy ozs to a troy lb unlike the usual 16oz to 1lb.
18 oz troy weight

Rounding dear old dad's share up they would need 3 weighings.
  • Put the 5oz weight on one tray and meassure out 5oz of gold.
  • Move the 5oz weight to the tray with the 5oz gold
  • Balance the scale with 10oz gold from the remaining 13oz
After 2 weighings there would be 3 piles of gold, 3oz, 5oz, 10oz

  • Put the 5oz weight on one tray along with the 3oz of gold
  • Balance the scale with 8oz of gold from the 10oz pile
After 3 weighings there would be 4 piles, 2oz, 3oz, 5oz, 8oz

give dad the 2oz pile, one son takes the the 3oz and 5oz pile leaving the other son the 8oz pile.
Well done oldman960!

I believe that is the correct answer. :thumbup:

(If someone can show me a way to do it in two weighings… I'll be really impressed. :P )

So,this week you get… an apple:
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