幾條數學問題(英文) [複製鏈接]

1.A mathmatics book with 200pages in 10mm thick. If the relative error is 1/500,fing the maximum absolute rreor of each page.

2.If 開方2=1.414,without using a calculator,fing the value of 4/開方32

3.The sum of two numbers is 143 and their difference is 9.Find these two numbers.Let the large number be x,the small number be y

4.If a=2b and b=5c,find the ratio a:b:c

5.135 sweets are divided among A and B in the ratio of 2:7.How many sweets does each person get?

6.The total salaries of A,B and C are $34000.If A's salary:B's salary =3:2 and B's salary : C's salary =3:1,find how much salarydoes each person get.

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（本人是中一，錯了別插）

1.A mathmatics book with 200pages in 10mm thick. If the relative error is 1/500,fing the maximum absolute rreor of each page.

Since, Relative Error= Maximum Absolute Error / Actual Value

Let x mm be the Maximum Absolute Error

x / 10mm = 1 / 500
500x = 10mm
x=0.02
Therefore, Maximum Absolute Error is 0.02mm

2.If 開方2=1.414,without using a calculator,fing the value of 4 / 開方32
Since 開方32 = 4  x 開方2
Therefore, 4 / 開方32
= 4 / (4 x 開方2)
= 4 / 4 x 1.414
=4 /  5.656
= 0.707(cor. to 3 sig. fig.)

3.The sum of two numbers is 143 and their difference is 9.Find these two numbers.Let the large number be x,the small number be y

Let x+y=143 be the first equation
Let x-y=9 be the second equation

equation 1 + equation 2
2x=152
x=76

substitute x=76 into equation 1
76+y=143
y=67
Therefore x equals 76 and y equals 67.

4.If a=2b and b=5c,find the ratio a:b:c

a=2b                                                  b=5c
a/b=2/1                                             b/c=5/1
a:b=2:1                                                b:c=5:1

a:b=2:1           b:c=5:1
a:b:c = 2x5:1x5:1x2
a:b:c=10:5:2

5.135 sweets are divided among A and B in the ratio of 2:7.How many sweets does each person get?

A gets: 135 x 2 / 2+7
            = 30 sweets
B gets: 135x 7 / 2+7
            = 105 sweets
Therefore A and B gets 30 sweets and 105 sweets respectively.

6.The total salaries of A,B and C are $34000.If A's salary:B's salary =3:2 and B's salary : C's salary =3:1,find how much salarydoes each person get.

A's salary:B's salary =3:2  and B's salary : C's salary =3:1
A's salary:B's salary:C's salary = 9:6:2

A gets: $34000 x 9 / 17
          = $18000
B gets: $34000 x 6 / 17
          = $12000
C gets: $34000 x 2 / 17
          = $4000
Therefore, A gets $18000, B gets $12000, C gets $4000

引用第2樓bon1於2008-07-15 00:48發表的  :
1.A mathmatics book with 200pages in 10mm thick. If the relative error is 1/500,fing the maximum absolute rreor of each page.
Since, Relative Error= Maximum Absolute Error / Actual Value
Let x mm be the Maximum Absolute Error
.......

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