F.3 Maths:( {急.!}

babe.3.

2010-10-25 5:38 am

The weight of a radioactive chemical decrease by 50% every 1600 years. If its original weight is 4 kg, what will its weight be after 19200 years?
(Give the answer correct to the nearest g.)

好急的`唔該晒=)`

更新1:

唔好意思.仲有一題.!` Last year, the annual rates payable for a flat were $5500. If the rateable value of this flat increase by 8% in this year, find the new quarterly rates payable by the owner. suppose the tax rate for rates is 5% each year.

回答 (2)

ShikaP

2010-10-26 4:51 am

✔ 最佳答案

1. it's weight after19200years
=4 * ((50%)^(19 200 / 1 600)) * 1 000 = 1g,cor to the nearest g

2.
the new quarterly rates payable by the owner
= 5500/0.05*0.08
=$8800

2011-03-28 22:56:59 補充：
e...so I got error???

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chauping

2010-10-25 5:40 am

4000g X 0.5^12 = 0.976g

2010-10-24 21:41:46 補充：
square root 12 because 19200yr/1600yr = 12

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