1. The price of beef was $16 per Kg. yesterday. It has risen 25% today and fall 25% tomorrow. What will be the price of 1 Kg. of beef tomorrow?
2. After spending some money, a boy has $40 left which is 20! of his pocket money. How much has he spent?
3. Find the amount obtained by depositig $2000 in a bank at simple interest rate of 10% per year for 3 years.
F.1Maths: Percentage 急!!!!!!!
2008-12-12 2:29 am
回答 (4)
2008-12-12 2:37 am
✔ 最佳答案
Q1)16 x ( 1+25% ) x ( 1-25% )
= 16 x 1.25 x 0.75
= $15/kg
Q2)
Let $Y be the money that he had in his pocket originally
$40 = 0.2Y
Y = $200
Q3)
simple Interest for 3 years:
2000 x 10% x 3
= 600
Therefore, the total amount is $2000 + $600 = $2600
2008-12-11 19:14:45 補充：
continue of Q2)...
he has $200 in his pocket originally. Therefore, he had spent $200 - $40 = $160.
參考: myself.. 勿抄!!
2008-12-12 7:57 am
1. The price of 1 Kg. of beef tomorrow
= 16 × (1+25%) × (1-25%) ... (original price × rise × fall)
= 16 × 125% × 75%
= 16 × 1.25 × 0.75
= $15
2. The money he has spent
= 40÷20% - 40 ... (original money - remaining money)
= 200 - 40
= $160
3. The amount obtained
= 2000 × (1+10%×3)
= 2000 × 130%
= 2000 × 1.3
= $2600
= 16 × (1+25%) × (1-25%) ... (original price × rise × fall)
= 16 × 125% × 75%
= 16 × 1.25 × 0.75
= $15
2. The money he has spent
= 40÷20% - 40 ... (original money - remaining money)
= 200 - 40
= $160
3. The amount obtained
= 2000 × (1+10%×3)
= 2000 × 130%
= 2000 × 1.3
= $2600
參考: me
2008-12-12 6:01 am
For Q2 &Q3
Q2:
Let Y is the money he has spent
(40 /(Y 40))x100=20%
40/(Y 40)=2/10
40=2/10Y 8
32=2/10Y
Y= 160
Q3:
2000 x (1 10%) x(1 10%) x(1 10%)
=2200 x(1 10%) x(1 10%)
=2420 x(1 10%)
=2662
Q2:
Let Y is the money he has spent
(40 /(Y 40))x100=20%
40/(Y 40)=2/10
40=2/10Y 8
32=2/10Y
Y= 160
Q3:
2000 x (1 10%) x(1 10%) x(1 10%)
=2200 x(1 10%) x(1 10%)
=2420 x(1 10%)
=2662
參考: Maths Cognition
2008-12-12 2:39 am
1.16X(1+25%)X(1-25%)
=20X(1-25%)
=$15
2.(40-20)
__________X100%
40
=50%
3.2000X(1+10%)X(1+10%)X(1+10%)
=$1458
=20X(1-25%)
=$15
2.(40-20)
__________X100%
40
=50%
3.2000X(1+10%)X(1+10%)X(1+10%)
=$1458
參考: ME
收錄日期: 2021-04-13 16:18:42
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