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答案：D
解析：
Choice (D) is correct. Let r be the number of red marbles in the jar. The probability of selecting a red marble is equal to the number of red marbles divided by the total number of marbles. Since the probability of selecting a red marble is 2/3.There are 36 green marbles and r red marbles, so the previous equation becomes 2/3=r/r+36. This simplifies to 2(r+36)=3r, or 2r+72=3r. Therefore, the number of red marbles, r, is 72.
| 重點單詞 | 查看全部解釋 | |||
| previous | ['pri:vjəs] |
想一想再看 adj. 在 ... 之前，先，前，以前的 |
聯想記憶 | |
| marble | ['mɑ:bl] |
想一想再看 n. 大理石 |
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| probability | [.prɔbə'biliti] |
想一想再看 n. 可能性，或然率，機率 |
聯想記憶 | |
| jar | [dʒɑ:] |
想一想再看 n. 不和諧，刺耳聲，震動，震驚，廣口瓶 |
聯想記憶 | |
| multiple | ['mʌltipl] |
想一想再看 adj. 許多，多種多樣的 |
聯想記憶 | |
| equation | [i'kweiʃən] |
想一想再看 n. 相等，方程(式), 等式，均衡 |
聯想記憶 | |
| random | ['rændəm] |
想一想再看 adj. 隨機的，隨意的，任意的 |
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