1.Difference between two numbers is 6 . The sum of these two numbers is 3 times of their difference.Find the larger number.
2.Mr. A and B have $ 300 all together . Mr.B $ 20 less than 1/4 of the amount that Mr.A has.How much does Mr A have ?
3.Joyce is 15 years old now , which is 1/3 of her mother's age. Her father is 8 years older than her mother . How old is her father now ?
代數式,要式
simple interest
1.$20000 is invested. A simple interest of $ 3000 is earned after 3 years.What is the interest rate of this bank?
2.What is the simple investing % 50000 in a bank for 2 years and 6 months at an annual rate of 4%?
3.Mr.Chan deposits $ 20000 in to Bank A at a rate of 5% and $ 30000 into Bank B at a rate of 6%. Two bank are in system of simple interest. How much will he have 3 years later ?
求高手解答,本人唔識DD野,求幫助,如果+msn 就更好
英文數學,求幫助
2012-08-26 6:17 am
回答 (2)
2012-08-26 6:46 am
✔ 最佳答案
1.Let the larger number be n, and the smaller number by m.
n - m = 6 ...... [1]
n + m = 3(n - m) ...... [2]
Put [1] into [2] :
n + m = 3(6)
n + m = 18 ...... [3]
[1] + [3] :
2n = 24
n = 12
Hence, the larger number is 12.
2.
Let $a be the amount that Mr. A has, and $b be the amount that Mr. B has.
a + b = 300 ...... [1]
b = (1/4)a - 20 ...... [2]
[1] - [2] :
a = 300 - (1/4)a + 20
4a = 1200 - a + 80
5a = 1280
a = 256
Hence, Mr. A has $256.
3.
Let m be the age of her mother now, and f be the age of her father now.
(1/3)m = 15 ...... [1]
f = m + 8 ...... [2]
From [1] :
m = 45
Put m = 45 into [2] :
f = (45) + 8
f = 53
Hence, his father is 53 years old.
1.
Let R% be the annual interest rate.
20000 x R% x 3 = 3000
R% = 0.05
R% = 5%
Hence, the annual interest rate is 5%.
2.
Simple interest
= $50000 x 4% x 2.5
= $5000
3.
Total interest
= $20000 x 5% x 3 + $30000 x 6% x 3
= $8400
參考: fooks
2012-08-26 6:31 am
3.Joyce is 15 years old now , which is 1/3 of her mother's age. Her father is 8 years older than her mother . How old is her father now ?
ANS: (15x3)+8
= 5 3
我只係識e題"- -
希望幫倒你小小啦~~
ANS: (15x3)+8
= 5 3
我只係識e題"- -
希望幫倒你小小啦~~
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