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teller

  • one year ago

Someone mind checking my work? The radioactive substance cesium-137 has a half-life of 30 years. The amount A(t) (in grams) of a sample of cesium-137 remaining after t years is given by the following exponential function. A(t)=381(1/2)^t/30 Find the initial amount in the sample and the amount remaining after 50 years. Round your answers to the nearest gram as necessary. initial amount = 381 after 50 years = 1270

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  1. anonymous
    • one year ago
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    What do you mean? I see no work. A radioactive substance would have less grams after 50 years. In other words, radioactive substances decreases in grams every year.

  2. teller
    • one year ago
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    I sent my work down below where it says initial amount = 381 after 50 years = 1270

  3. teller
    • one year ago
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    I plugged the information into my online calculator and that's what I got after 50 years.

  4. anonymous
    • one year ago
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    You could at least say you plugged it in. There was no indicator to what you did except put in the answer.

  5. anonymous
    • one year ago
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    Because I dont think you plugged it right.

  6. teller
    • one year ago
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    A(50)=381(1/2)^50/30 got me 1270

  7. anonymous
    • one year ago
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    \[381 \times (0.5)^{\frac{ 50 }{ 30 }}\]

  8. teller
    • one year ago
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    But my thing says to use the formula A(t)=381(1/2)^t/30

  9. anonymous
    • one year ago
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    Same thing.... (1/2)=0.5

  10. teller
    • one year ago
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    120.00748

  11. teller
    • one year ago
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    That's what I got.

  12. teller
    • one year ago
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    so rounding it would make it 120?

  13. anonymous
    • one year ago
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    Yea me too.

  14. teller
    • one year ago
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    Alright thank you

  15. anonymous
    • one year ago
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    No problem!

  16. mathmate
    • one year ago
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    @teller Remember PEMDAS: A(t)=381(1/2)^t/30 equals A(t)=381[(1/2)^t]/30 which is not correct. You need to write A(t)=381(1/2)^(t/30) or else calculators will give wrong numbers. Calculators go strictly with PEMDAS, doesn't know what you want! xD

  17. anonymous
    • one year ago
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    Yes exactly. I tried figuring out what @teller did wrong, but couldnt figure on how to get 1270.

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