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數學題(英文)

自由人

2009-08-14 4:34 am

唔該...我有幾題數學題(英文)唔識做...
麻煩幫幫忙

1.Simplify the following ratios.

(a)1:3/4

(b)5cm:1/4m

2.If a:b=1:2 and b:c=3:2,find the ratio of a:b:c.

3.If a:b=2:3 and b:c=5:1,find the ratio of a:b:c.

4.In the figure,BC:CD=2:3.Find area of triangleABC:area of triangleACD.

5.The scale of a map is 1cm:30km.Find the distance on the map if the actual distance
between 2 stations is 60km.

6.Simplify the following ratios.

(a)1/3:2/4:2/6

(b)300ml:0.1L:5L

7.If a=3b and b=9c,find a:b:c.

8.Sam and Ray share $180 pocket money in a ratio of 4:5.How much does each boy
have?

9.The figure shows 3 equilateral triangles.The ratio of their sides is 2:3:4.If the area of the largest one is 80 cm(square),find the area of the other two triangles.

10.The figure is the cross-section of a prism.If the volume and height of that prism are 450cm(3次方) and 18cm respectively,find the cross-sectional area.

麻煩晒~我要詳細算式!!我想明白點計...注明題號~
當然要有答案!!

回答 (1)

Herman Tam

2009-08-14 5:55 am

✔ 最佳答案

Question 1
Simplify the following ratios.

(a)1:3/4
=1/(3/4)
=1*(4/3)=4/3
=4:3

(b)5cm:1/4m
=5cm:(0.25*100cm)
=5cm: 25cm
=1:5

Question 2
If a:b=1:2 and b:c=3:2,find the ratio of a:b:c
a:b=1:2, b:c=3:2
a:b=1:2=>a/b=1/2=>b=2a=>a=1/2 b
b:c=3:2=> b/c=3/2=> c=2/3b
a:b:c=1/2b:b:2/3b
=1/2:1:2/3
(Multiply all by 6)
=3:6:4

Question 3
If a:b=2:3 and b:c=5:1,find the ratio of a:b:c
a:c=2:3=>a/b=2/3=>a=2/3b
b:c=5:1=> c=1/5b
a:b:c=2/3b:b:1/5b
=2/3:1:1/5
(Multiply all by 15)
=10:15:3

Question 5
The scale of a map is 1cm:30km.Find the distance on the map if the actual distance between 2 stations is 60km.

The distance on the map between 2 stations
=(1cm/30km)*60km
=1cm/30 *(60)
=2cm

Question 6
(a)1/3:2/4:2/6
=1/3:1/2:1/3
(Multiply all by 6 at the same time)
=2:3:2

(b)300ml:0.1L:5L
=0.3L:0.1L:5L
=0.3:0.1:5
(Multiply all by 10)
=3:10:50

Question 7
If a=3b and b=9c,find a:b:c.
a=3b
b=9c=> c=1/9b
a:b:c=3b:b:1/9b
=3:1:1/9
(Multiply all by 9)
=27:9:1

Question 8
Sam and Ray share $180 pocket money in a ratio of 4:5.How much does each boy have?
Sam gets $180 * 4/(4+5) =$80
Ray gets $180 -$80 =$100

Question 4, 9 and 10
You do not provide the figure. How to calculate?

參考: ME

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