Question

$1980$ 年一月，莫纳罗亚观测站记录的二氧化碳 CO_$2$ 浓度为 $338$ ppm（百万分之一）。此后，CO_$2$ 的年平均读数每年约增加 $1.515$ ppm。预计 $2030$ 年一月的 CO_$2$ 浓度是多少 ppm？将答案四舍五入到最接近的整数。

In January $1980$ the Mauna Loa Observatory recorded carbon dioxide CO_$2$ levels of $338$ ppm (parts per million). Over the years the average CO_$2$ reading has increased by about $1.515$ ppm each year. What is the expected CO_$2$ 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

小提示：

从 $1980$ 年一月到 $2030$ 年一月有 $50$ 年

There are $50$ years from January $1980$ to January $2030$

大提示：

估算 $50\cdot1.515$ ，再加上 $1980$ 年的水平

Estimate $50\cdot1.515$ , then add the $1980$ level

视频讲解：

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文字解答：

从 $1980$ 年到 $2030$ 年相隔 $50$ 年，所以预计到 $2030$ 年，CO_$2$ 读数将增加约 $50 \times 1.515 = 75.75 \approx 76$ ppm。由于 $1980$ 年的 CO_$2$ 读数是 $338$ ppm，所以到 $2030$ 年的预计读数为 $338 + 76 = 414$ ppm。

正确答案是 B。

There are $50$ years between $1980$ and $2030$ , so we can expect the CO_$2$ reading to increase by $50 \times 1.515 = 75.75 \approx 76$ ppm by $2030$ . Since the CO_$2$ 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