F.1數學題目II

4) new amount = 80, original amount =50,
percentage increase=(80-50)/50 *100%=60 %//

5) increased amount = 30, original amount = 200m
percentage increase=30/200 * 100%=60%//

6)當有 selling price and percentage profit,
cost price=selling price x (1+percentage profit)

7) The selling price of a TV set is $4675. If it is sold at a loss of 15%
cost price=selling price x (1+percentage profit)=4675*(1-15%)=5500//

4) new amount = 80, original amount =50,
percentage increase=(80-50)/50 *100%=60 %//

5) increased amount = 30, original amount = 200m
percentage increase=30/200 * 100%=60%//

6)當有 selling price and percentage profit,
cost price=selling price x (1+percentage profit)

7) The selling price of a TV set is $4675. If it is sold at a loss of 15%
cost price=selling price x (1+percentage profit)=4675*(1-15%)=5500//

4) new amount = 80, original amount =50, percentage increase=?

將new amount 減original amount 就等於多左的錢，將多左的錢除original amount 就知道在original amount 中佔左多少，之後 乘 100% 就等於 percentage increase!!!
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＝３０／５０×１００／１％
＝３／５×１００／１％
＝６０％

5) increased amount = 30, original amount = 200m percentage increase= ?

佢original amount除以 increased　amount，我地就知道佢的ｎｅｗ　ａｍｏｕｎｔ（即係２００裏面佔幾多），之後乘１００％就知道 percentage increase！！
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＝３／２０×１００／１％
＝１５％

2題個分母都要係original amount係因為original amount 是原本的設定值，不能改變的！

6)當有 selling price and percentage profit, 點求 cost price?
係～

7) The selling price of a TV set is $4675. If it is sold at a loss of 15%, What is the cost price?

當部電視賣$4675 , 但係佢賣出去就loss左15% , 只要先搵出佢賣出去的%(即係1一15%)之後用電視的selling price除返佢賣出去的% , 就知佢的cost price!!!
４６７５÷（１－１５％）
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＝４６７５÷８５／１００％
＝＄５５００

好開心你升上f.1 , 我舊年都係f.1 , 又係英中 , 所以,以上的數學題我都識(學過)!!
＾－－＾

Percentage increase(增長百分率)=(new amount - original amount)/original amount *100%
=(新-舊)/舊*100%
Reason for the original amount be the denominator(分母) :
試想想:你想計下一樣野貴唑幾多時,你會點計.
1個蘋果賣$5,後來加價,變了$8,那貴了:$3
即係以百分比計算時貴唑幾多?
你就應以之前的價錢做分母,以作標準,所以會變成
(8-5)/5 *100%= 60%

同樣地,在你的問題中,
4) 舊值=50,新值=80
所以要以50來做標準,去睇下以百分比計算增長了幾多.
percentage increasae = (80-50)/50 *100%

5) 今次,提供了(increased amount)同(original amount),不過也是一樣.
percentage increase = 30/200m *100%
(注意:30 = 230m - 200m)

6)呢d公式要背熟: Profit = Selling Price - Cost Price
Percentage profit = (Selling Price - Cost Price)/Cost Price *100%
so,Selling Price = Cost Price *(1+ Percentage Profit)
所以,你個cost price只要轉變少少就計到..
Cost Price = Selling Price / (1+ Percentage Profit)

7)Let the cost price be $c,
(c - 4675)/c = 15%
0.15c = c - 4675
c = 5500
so,the cost price is $5500.
這條是用percentage loss的公式,
因為係loss,即係成本(cost)大過售價(selling price),
Loss = cost - selling price

不過要注意:計cost過d數時,cost一定在分母
計original amount過d數時,original amount一定在分母.
希望幫到你,謝謝!

4) new amount = 80, original amount =50, percentage increase=?

新總數=80, 全總數=50, 問增加百分比是?

ans: 新總數 - 舊總數 / 舊總數 x 100%
= (80-50/50)x100%
= (30/50)x100%
=0.6x100%
=60%

5) increased amount = 30, original amount = 200m percentage increase= ?

同上面一樣:

ans: 增加數 / 舊總數 x 100%
= (30/200)x100%
=0.15x100%
=15%

解釋~ AND我想問下點解哩2題個分母都要係original amount?
ans: 因為百分比要以舊總數(original amount)為基礎

6)當有 selling price and percentage profit, 點求 cost price?

selling price = 售價
percentage profit = 利潤百分比
cost price = 成本

ans: 成本x利潤百分比=售價

例如: selling price = $120
percentage profit = 20%

cost price x (1 + percentage profit) = selling price
cost price x 120% = $120
cost price x (120/100) = $120
cost price = $120 x (100/120)
= $120 x (5/6)
= $100

7) The selling price of a TV set is $4675. If it is sold at a loss of 15%, What is the cost price?

ans: cost price x (1 + percentage profit) = selling price
cost price x [1 + (-15%)] = $4675
cost price x 85% = $4675
cost price x (85/100) = $4675
cost price = $4675 x (100/85)
= $4675 x (20/17)
=$5500

4) ans: (80-50) / 50 = 0.6 => 60% -> (80-50) 係你增加左既量
5) ans: 30 / 200 = 0.15 => 15% -> 30 好直接講增加左幾多啦

而分母係original, 係因為基本數值, 如 原本係1 增加 1 -> 1/1 = 100% & 2 增加2 -> 2/2=100%

6) ans: selling price -> new amount; original amount -> cost price; percentage profit -> 1+percetnage increase

=> selling = cost * (1+profit)
=> cost = selling / (1+profit)

7) cost = 4675 / (1+(-0.15))
=> cost = 4675 / (0.85)
=> cost = 5500

即係85折

4)新的總數 = 80, 本來的總數=50, 百份比增加=?
5)新的總數 = 30, 本來的總數 = 200m ,百份比增加= ?
因為計percentage increase的公式係:
新的總數-本來的總數
--------------------------------x 100%
本來的總數
6)公式係:
let x be the cost price:
selling price - x
--------------------------------------x 100% = percentage profit
x

7)電視機的售價是$4675,如果它的售價會有15%的損失,成本是多少?

我讀form4..都係英中
有咩唔明最緊要多問啊~
畀心機=]