3.A new town has a population of 300000, and it grows by 8% every year. Now the town has a reservoir that can supply water for 400000 people.When will the town need a new reservoir?
這條題目是growth~~
幫我解答下啦~~ ^_^
f.2maths (請過來啦!!) (3)
2007-02-03 3:11 am
回答 (3)
2007-02-03 3:27 am
✔ 最佳答案
300000 x 8%=24000
(400000-300000)/24000
=100000/24000
=4(1/6)
The town will need a new reservoir about 4 years and 2 months later.
參考: 數學能手Me
2007-02-03 4:10 am
設n是年
300000×(1+8%)^n＞400000
(1+8%)^n＞4/3
n log 1.08＞log 4/3
n＞(log 4/3 ) / log 1.08
n＞3.74
n=4
∴要4年
300000×(1+8%)^n＞400000
(1+8%)^n＞4/3
n log 1.08＞log 4/3
n＞(log 4/3 ) / log 1.08
n＞3.74
n=4
∴要4年
參考: king
2007-02-03 3:43 am
300000 x 8%
=24000
(400000-300000)/24000
=100000/24000
=4(1/6)
=24000
(400000-300000)/24000
=100000/24000
=4(1/6)
收錄日期: 2021-04-12 23:20:56
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070202000051KK02622