Perth mint assay maths error

Discussion in 'Gold' started by Jayden, Jun 18, 2020.

  1. Jayden

    Jayden Active Member Silver Stacker

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    Hi guys

    Just a little thing I found when doing the maths on the Perth mint assay bars. The 20g bar has a bit of a error when it comes to AGW in Troy Oz

    Decimal accuracy has been maintained using the full weight of a Troy Oz to 7 decimal places (31.1034768g) to prevent rounding errors
    / = divide

    20g / 31.1034768
    = 0.64301493 oz
    The mint states it’s 0.640 oz on the packaging, giving a difference of 0.003 Troy Oz
    0.640 x 31.1034768 = 19.9062252g
    So it’s almost 0.1g under weight, yet the minimal gross weight states 20g with the assumption of no weight variance from design in this instance.


    The others are all pretty close as shown below
    1g
    Label = 0.032oz
    Calc = 0.03215075oz
    Dif = Less than 3DP

    5g
    Label = 0.161oz
    Calc = 0.16075373oz
    Dif = Less than 3DP

    10g
    Label = 0.320oz
    Calc = 0.32150747oz
    Dif = 0.00150747oz

    50g
    Label = 1.607oz
    Calc = 1.60753733
    Dif = Less than 3DP

    100g
    Label = 3.215oz
    Calc = 3.21507466
    Dif = Less than 3DP

    Anyone know the reasoning for this?
    Keen to hear what you guys think :)
     
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  2. KangaBanga

    KangaBanga Member

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    Did u weigh ur 20g bar? If it's 20g then dun care too much about the oz conversion, u got what u paid for.. Perth mint calls their shishi coins pixiu, English is not there string suit..
     
  3. Eureka Moments

    Eureka Moments Well-Known Member Silver Stacker

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    I bought stuff from a scungy dealer going way back but not coins.
     
  4. Jason1

    Jason1 Well-Known Member

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    Maybe the learnt English at the same place you did. ahaha
     
  5. KangaBanga

    KangaBanga Member

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    I highly doubt they did. ;) Lol.
     
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