AMC8 1996

AMC8 1996 · Q7

AMC8 1996 · Q7. It mainly tests Exponents & radicals, Patterns & sequences (misc).

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?

Brent的金鱼每月增加到四倍（数量变为原来的四倍），Gretel的金鱼每月增加到两倍。如果Brent有4条金鱼时Gretel有128条金鱼，那么从那时起多少个月后它们金鱼数量相同？

(A) 4 4

(B) 5 5

(D) 7 7

(E) 8 8

Answer

Correct choice: (B)

正确答案：（B）

Solution

Month 0: Brent 4, Gretel 128; Month 1: 16,256; Month 2:64,512; Month 3:256,1024; Month 4:1024,2048; Month 5:4096,4096. Equal in 5 months.

第0个月：Brent 4, Gretel 128；第1个月：16,256；第2个月：64,512；第3个月：256,1024；第4个月：1024,2048；第5个月：4096,4096。5个月后相等。

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