pharmacy math brain teaser




The pharmacy has an old style balance scale
like the one above.

You have only two measuring counter weights:

• 30 grams
• 5 grams

Divide 300 grams of powder medicine
into 3 groups:

• one of 150 grams
• one of 100 grams
• one of 50 grams.

BUT... You can only weigh 3 times. Which means you can keep adding powder and manipulate the weights. But, when you take the powder off the scale, that's a final weight.

How would you do this and only use the scale for 3 measurements?

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pharmacy math brain teaser

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Easiest way I could think of
by: Anonymous

I would start with the 30 gram weight on one side and counter balance. Then I'd take off the 30 gram weight and counter balance so both sides have 30 grams of powder. Next I'd put the 5 gram weight on one side and counter balance so I have 35 grams of powder on one side and 30 (with the 5 gram weight) on the other. then I would take the 5 gram weight and put it on the other side to make it 40 grams and once again counter balance to make 40 grams of powder on both side. I would do this process 2 more until both sides had 50 grams of powder. Finally i would take the powder off one side for the 50 and keep counter balancing the 50 grams on the other side until i had 3 groups of powder (50g,100g, and 150g).

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