percentages questions

👨🏻‍🏫 學術台數學

Bluee

2007-10-28 1:36 am

1) A kind of endangered birds decreases by 40% each year. If 1944 endangered birds of that kind are left at present, how many were there 4 years ago?

回答 (1)

2007-10-28 2:11 am

✔ 最佳答案

Let y be the number of endangered birds 4 years ago.

y(1-0.4)^4=1944

y=1944/0.6^4

=15000

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