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x3_drummerchick

  • one year ago

How do i solve this!? Will give medals! Radium-221 has a half-life of 30 sec. How long will it take for 84% of a sample to decay? (Round your answer to the nearest whole number.)

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  1. x3_drummerchick
    • one year ago
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    @Nnesha

  2. x3_drummerchick
    • one year ago
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    @Jhannybean

  3. x3_drummerchick
    • one year ago
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    @dan815

  4. dan815
    • one year ago
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    okay so basically

  5. dan815
    • one year ago
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    we keep losing 1/2 ever 30 seconds

  6. x3_drummerchick
    • one year ago
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    i found the 'r' by doing ln2/30

  7. dan815
    • one year ago
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    wait i have to figure it out too

  8. dan815
    • one year ago
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    |dw:1443224796743:dw|

  9. dan815
    • one year ago
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    |dw:1443224894019:dw|

  10. dan815
    • one year ago
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    then we multiply 30*n to see how many seconds

  11. x3_drummerchick
    • one year ago
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    im confused

  12. dan815
    • one year ago
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    okay let me see how to explain this

  13. x3_drummerchick
    • one year ago
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    oohhh wait wait i think i know what you mean

  14. x3_drummerchick
    • one year ago
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    you start with 1 mg

  15. x3_drummerchick
    • one year ago
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    i mean, 1 "sample" of it, right?

  16. dan815
    • one year ago
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    yep

  17. x3_drummerchick
    • one year ago
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    okay, and howd you get the (1/2)?

  18. dan815
    • one year ago
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    okay so forget like the 30 secs to begin with i mean remember it but we really wanna see how many half lives have passed we just know 1 half live is 30 seconds keep that in mind

  19. x3_drummerchick
    • one year ago
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    Okay

  20. dan815
    • one year ago
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    basically like this, now you know that for every half life we multiply by a 1/2

  21. x3_drummerchick
    • one year ago
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    okay

  22. dan815
    • one year ago
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    |dw:1443225179484:dw|

  23. x3_drummerchick
    • one year ago
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    okay that makes sense

  24. x3_drummerchick
    • one year ago
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    so how would we incorporate that into the formula?

  25. x3_drummerchick
    • one year ago
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    |dw:1443225321392:dw|

  26. dan815
    • one year ago
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    okay

  27. x3_drummerchick
    • one year ago
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    |dw:1443225534573:dw|

  28. dan815
    • one year ago
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    every 30 secs u want a new half lige so

  29. dan815
    • one year ago
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    life

  30. x3_drummerchick
    • one year ago
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    okay

  31. dan815
    • one year ago
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    |dw:1443225561434:dw|

  32. dan815
    • one year ago
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    i believe this works

  33. dan815
    • one year ago
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    let me thing hmm

  34. dan815
    • one year ago
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    think

  35. x3_drummerchick
    • one year ago
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    here is an example layout, but doesnr have answers, it confused me

    1 Attachment
  36. x3_drummerchick
    • one year ago
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    i dont know if that helps any

  37. dan815
    • one year ago
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    gimme a few mins, i am dealing with someone here

  38. x3_drummerchick
    • one year ago
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    okay

  39. dan815
    • one year ago
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    yeah dont worry ill help u understand this stuff its pretty simple

  40. x3_drummerchick
    • one year ago
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    okay thanks!

  41. x3_drummerchick
    • one year ago
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    actually i think i figured it out!

  42. dan815
    • one year ago
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    waiitt okay

  43. dan815
    • one year ago
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    i want to show u something important first

  44. dan815
    • one year ago
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    are you there

  45. x3_drummerchick
    • one year ago
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    crap, nvm i got it wrong

  46. dan815
    • one year ago
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    okay remember the (1/2)^n formula

  47. x3_drummerchick
    • one year ago
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    yeah

  48. dan815
    • one year ago
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    now lets tweak that a little bit okay we know that for evert 30 secs we want it to be halved so

  49. dan815
    • one year ago
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    1*(1/2)^(t/30)

  50. dan815
    • one year ago
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    now u see every 30 secs we would exactly half it

  51. dan815
    • one year ago
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    the equation they give u is this just in disguise

  52. x3_drummerchick
    • one year ago
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    that makes sense

  53. dan815
    • one year ago
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    like for example

  54. dan815
    • one year ago
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    if we apply e^ln(x) = x e and ln cancel out right

  55. dan815
    • one year ago
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    lets apply to that equation we know has to be right

  56. x3_drummerchick
    • one year ago
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    okay

  57. dan815
    • one year ago
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    e^ln((1/2)^(t/30))

  58. dan815
    • one year ago
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    do you know your ln rules like ln(x^3)= 3 ln x the power multiples

  59. x3_drummerchick
    • one year ago
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    oh wait, dont you bring it to the rfont of the ln?

  60. x3_drummerchick
    • one year ago
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    front *

  61. dan815
    • one year ago
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    |dw:1443226339275:dw|

  62. dan815
    • one year ago
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    with a little bit of manipulation we see that the equation is exactly reuivalent

  63. dan815
    • one year ago
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    equivalent

  64. dan815
    • one year ago
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    there is only 1 rule im applying here over and over

  65. dan815
    • one year ago
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    |dw:1443226451939:dw|

  66. x3_drummerchick
    • one year ago
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    yes i do remember those

  67. dan815
    • one year ago
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    okay go ahead fill it all in now

  68. x3_drummerchick
    • one year ago
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    |dw:1443226609625:dw|

  69. dan815
    • one year ago
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    yes that is correct

  70. dan815
    • one year ago
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    http://prntscr.com/8kirao

  71. x3_drummerchick
    • one year ago
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    i got 79.33, is that right?

  72. x3_drummerchick
    • one year ago
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    seconds

  73. dan815
    • one year ago
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    i am not using a calculator make sure u round it to the 10th

  74. x3_drummerchick
    • one year ago
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    its correct :) thank you again so much, youre awesome!

  75. dan815
    • one year ago
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    okay you're welcome :)

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