Question

Brent 的金鱼每月变为原来的四倍，Gretel 的金鱼每月变为原来的两倍。如果某一时刻 Brent 有 $4$ 条金鱼，而 Gretel 有 $128$ 条金鱼，那么从那时起多少个月后，他们会有相同数量的金鱼？

Brent has goldfish that quadruple (become four times as many) every month, and Gretel has goldfish that double every month. If Brent has $4$ goldfish at the same time that Gretel has $128$ goldfish, then in how many months from that time will they have the same number of goldfish?

$4$

$5$

$6$

$7$

$8$

答案：B

知识点：等比数列指数

难度评级：860

解答：

Brent 的数量依次为 $4, 16, 64, 256, 1024, 4096$ ，Gretel 的数量依次为 $128, 256, 512, 1024, 2048, 4096$ 。

$5$ 个月后，两人都有 $4096$ 条。

所以正确答案是 B。

Brent's counts are $4, 16, 64, 256, 1024, 4096$ , and Gretel's are $128, 256, 512, 1024, 2048, 4096$ .

They are equal after $5$ months, when both have $4096$ .

Thus, the correct answer is B .

1996 AMC 8 第 7 题

答案：B

难度评级：860

解答：

其他年份的第 7 题