1) Last term, Peter obtained 90 marks in his English test but this term his mark was 72.By what percentage did his English result decrease?
我想問點解呢題個分母係72而唔係90?
2)MTR fares are increased by 8%. Find
(a) the new fare of a journey which costs $7.5 before the increase,
(b) the original fare of a journey which costs $5.4 after the increase.
唔識點計...解釋埋比我聽點解咁計...[IN CHINESE PLS~]
3)當有 decreased amount and percentage decrease,點求ORIGINAL AMOUNT?
F.1數學題目..
2007-08-11 6:02 am
回答 (2)
2007-08-11 11:58 pm
✔ 最佳答案
1)因為條式係---相減後除舊x100%一定係除舊數！
so分母係72
2a) new fare
$7.5x(1+8%)
=$8.1
>>$7.5係原本的價錢(before the increase), 現加8%,so(1+8%)
b) original fare
$5.4/(1+8%)
=$5
>>$5.4係加左價後的價錢(after the increase), 原因見下
>>原價x(1+percentage increase)= increased amount
3) ORIGINAL AMOUNT x (1-percentage decrease) = decreased amount
-->ORIGINAL AMOUNT =decreased amount /percentage decrease
記住條式，就會覺得簡單！
2007-08-11 6:15 am
1)90
2a)new fare=$7.5*(1+8%)
因為$7.5係未加價既fare...now增加左8%...so係$7.5+$7.5*(8%)=$7.5*(1+8%)
b)original fare=$5.4*(1-8%)
因為$5.4係加左價既fare...已經增加左8%...original fare係(1-8%) of$5.4...so係$5.4*(1-8%)
3)我吾係好肯定不過應該係decreased amount除以(1-percentage decrease)咁就可以求到ORIGINAL AMOUNT!!!我諗係!!不過吾知點解釋俾你知!!
hope可以幫到你!!
2a)new fare=$7.5*(1+8%)
因為$7.5係未加價既fare...now增加左8%...so係$7.5+$7.5*(8%)=$7.5*(1+8%)
b)original fare=$5.4*(1-8%)
因為$5.4係加左價既fare...已經增加左8%...original fare係(1-8%) of$5.4...so係$5.4*(1-8%)
3)我吾係好肯定不過應該係decreased amount除以(1-percentage decrease)咁就可以求到ORIGINAL AMOUNT!!!我諗係!!不過吾知點解釋俾你知!!
hope可以幫到你!!
參考: 我我我from3
收錄日期: 2021-04-13 01:02:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070810000051KK05870