推 wickedboy : 該不會是考"consecutive year"吧...所以第二小時才 06/23 22:34
→ wickedboy : 開始衰退? 06/23 22:34
→ wickedboy : hour 06/23 22:34
推 Pin0307 : 印象中這題補習班講義給的答案是錯的上課有改回來 06/24 02:19
At the start of an experiment, 10 grams of a certain isotope are present. The
isotope decays in such a manner that at the end of each consecutive hour,
1/2 of the amount of the isotope that was present at the beginning of the
hour remains. After N hours, between 1 and 0.1 gram of the isotope remains.
Which of the following could be the value of N?
[ Indicate all such values. ]
[A] 2 [B] 3 [C] 4 [D] 5 [E] 6 [F] 7 [G] 8 [H] 9
為什麼答案不是CDE呢?
10 ---> 5 ---> 2.5 ---> 1.25 ---> 0.625 ---> 0.3125 ---> 0.15625 ---> 0.078125
過了 1 2 3 4 5 6 7 小時
所以過了4~6小時 同位素的質量會界在0.1和1之間
請問我的計算哪邊有錯
謝謝
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※ 編輯: woody3724 (163.26.36.153), 06/23/2016 22:27:12
※ 編輯: woody3724 (163.26.36.153), 06/23/2016 22:28:50