Math. Have answer, please show work

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In a tracer method the potassium isotope 42K is used for labelling. The half life of 42K is 12.5 hours. If No is original number of atoms, how many hours will it take until only (1/1024) No Atoms remain?

The answer is 125 hours but I do not know how to get this. Please help!

  • Math. Have answer, please show work -

    Goodness.

    change the prior problem to

    1/1024=(1/2)^(t/12.5)

  • Math. Have answer, please show work -

    2 to the what = 1024 ?

    (If you do not know instantly do this
    2^x = 1024 )

    x log 2 = log 1024
    x = 10
    so
    (1/2)^10 = 1/1024
    t/12.5 = 10
    t = 125

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