Question

Josanna 到目前为止的考试成绩是 $90$ ， $80$ ， $70$ ， $60$ ，和 $85$ 。她的目标是在下一次考试后，把平均分至少提高 $3$ 分。她下一次考试至少需要多少分才能达到目标？

Josanna's test scores to date are $90,$ $80,$ $70,$ $60,$ and $85.$ Her goal is to raise her test average at least $3$ points with her next test. What is the minimum test score she would need to accomplish this goal?

$80$

$82$

$85$

$90$

$95$

答案：E

知识点：平均数

难度评级：880

解答：

前五次总分为 $90+80+70+60+85=385$ ，平均分为 $77$ 。目标是新的平均分至少为 $80$ 。

六次考试平均 $80$ 分需要总分 $6\cdot80=480$ ，因此第六次至少需要 $480-385=95$ 。

所以正确答案是 E。

The five scores sum to $90+80+70+60+85=385,$ giving an average of $77.$ The goal is a new average of at least $80.$

Six tests averaging $80$ must total $6\cdot80=480,$ so the sixth score must be at least $480-385=95.$

Thus, the correct answer is E.

2011 AMC 12B 第 2 题

答案：E

难度评级：880

解答：

其他年份的第 2 题