[10分] Maths Questions (Rate and Ratio) 要列明步驟 thx =]

2007-08-16 6:24 pm

1. In a school, the number of boy scouts and that of girl guides are in the ratio 3:5. If there are 8 more girl guides than boy scouts, find the total number of boy scouts and girl guides in the school.

2. A copper wire 108cm long is bent to from a triangle, in which the lengths are in the ratio 3:4:5. Find the length of the longer side of the triangle.

回答 (1)

鈴

2007-08-16 6:47 pm

✔ 最佳答案

1/ Assume the number of the boy scouts is X, and that of the girl guides is Y.
Since, the ratio of the number of the boy scouts and that of the girl guides = 3:5
Thus, X:Y=3:5
5X = 3Y--------(1)
And
Y - X = 8
Y = X + 8--------(2)

Sub (2) into (1),
5X = 3Y
5X = 3 (X + 8)
5X = 3X + 24
2X = 24
X = 12

Sub X = 12 into (2)
Y = X + 8
Y = 12 + 8
Y = 20

Thus, There are 12 boy scouts and 20 girl guides in the school.

2/ The length of the longest side = [ 108 x 5/ (3+4+5) ]cm
=(108 x 5/12)cm
=45cm

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