Question

一九八〇年一月，Mauna Loa 观测站记录的二氧化碳 CO₂ 水平为 $338$ 百万分率。多年中，平均 CO₂ 读数每年约增加 $1.515$ 百万分率。预计二〇三〇年一月的 CO₂ 水平是多少百万分率？答案四舍五入到最接近的整数。

In January 1980 the Mauna Loa Observatory recorded carbon dioxide CO₂ levels of $338$ ppm (parts per million). Over the years the average CO₂ reading has increased by about $1.515$ ppm each year. What is the expected CO₂ level in ppm in January 2030? Round your answer to the nearest integer.

$399$

$414$

$420$

$444$

$459$

答案：B

知识点：等差数列小数估算

难度评级：960

视频讲解：

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文字解答：

从 $1980$ 到 $2030$ 相隔 $50$ 年，所以预计到 $2030$ 年增加约 $50 \times 1.515 = 75.75 \approx 76$ 百万分率。以 $1980$ 年的 $338$ 百万分率为基础，到 $2030$ 年预计读数为 $338 + 76 = 414$ 百万分率。

正确答案是 B。

There are $50$ years between $1980$ and $2030$ , so we can expect the CO₂ reading to increase by $50 \times 1.515 = 75.75 \approx 76$ ppm by $2030$ . Since the CO₂ reading in $1980$ was $338$ ppm, then we will have $338 + 76 = 414$ ppm by $2030$ .

Thus, B is the correct answer.

2024 AMC 8 第 10 题

答案：B

难度评级：960

视频讲解：

文字解答：

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