F.1數學題10分!!!急急急!!

1.a) 3(1+20%) 3.6 36 4
---------------- = ------- = ------ = ---
5(1-10%) 4.5 45 5

1.b) 4/5 - 3/5 0.2
------------- x 100% = ----- x 100% = - 20%
3/5 3/5
∴該數的百份變化為 -20%

2.a) 佢原本重48+2=50kg
48-50
--------- x 100% = -0.04 = -4%
50

2.b) 佢本星期重 48-1.2 = 46.8 kg
46.8 - 48
-------------- x 100% = -0.025 = -2.5%
48

3) 設該正方體原本既邊長是x
則該正方體新既邊長是x(1-10%)
x(1-10%) - x 0.9x - x x(0.9-1)
-------------------- x 100% = ------------ x 100% = ----------- x 100% = -10%
x x x

4) 1.62 - 1.5
---------------- x 100% =0.08 = 8%
1.5
∴他身高的百份變化是+8%

5) 7.88 - 8
------------- x 100% = -0.015 = -1.5%
8
∴該枝金屬棒長度的百分減少是-1.5%

6) 更正後翠珊測驗分數是 80-6=74
74 - 80
----------- x 100% = -0.075 = -7.5%
80

∴更正後翠珊測驗分數的百分減少是 - 7.5 %

1a.分子=3X(1+20%)=3.6
分母=5X(1-10%)=4.5
新分數=3.6/4.5=4/5
1b.(4/5-3/5)分之3/5X100%
=1/5分之3/5X100%
=1/5X5/3X100%

=33又3分1%

2a.
2/48+2X 100%
=4%

2b.
1.2/48 X100%

=2.5%

3.減少了=L cm X 10%=0.1L cm
減少了的邊長=L cm - 0.1L cm=0.9L cm
減少了的體積=[L^3-(0.9L)^3]
減少了的體積=(L^3-0.729L^3)
減少了的體積=0.271L^3 立方厘米
百分數=0.271L^3/L^3 X100%
=27.1%

4. 1.62-1.5/1.5 X 100%

= 0.12/1.5 X100%
=8%

5.
8 - 7.88/8 X100%

= 0.12/8 X100%

=1.5%

6. 她的分數:

= 6/80 X 100%
=7.5%

1. {(3/5)/[(3*120%)/(5*90%)]}*100%=33%
2. 2/48*100%=4.16% 1.2/46*100%=2.6%
3. {[(L*90%)(L*90%)(L*90%)]/(L*L*L)}
4. (1.62-1.5)/1.5*100%=(0.12/1.5)*100%=0.08*100%=8%
5. (0.788/8)*100%=0.12/8*100%=0.015*100%=1.5%
6. 6/80*100%=7.5%

若分數3/5既分子增加左20%,而分母減少左10%,)求變化後新既分數。
求該數既百分增加或減少。.曼凝上星期參加健身計劃後體重只有48kg,共減輕了2kg。)求佢體重既百分減少。
若曼凝本星期繼續參加健身計劃,還計劃再減1.2kg,問佢本星期體重既百分減少系幾多?

一正方體既邊長減少左10%,求該正方體體積既百分減少。
(提示:設原來正方體既邊長為L cm...)