Mathematics

1. a/b=b/c=4
a=4b and c=b/4
a:b:c
=4b:b:b/4
=16b:4b:b
=16:4:1

2.A pizza is first divided into two parts A and B in the ratio 3:5 by area. The larger part is further divided into two parts C and D in the ratio 3:5 by area. Find the ratios of areas of

(a) Let the area of whole pizza be 8x
we have area A:area B=3x:5x
and Area C =3x/8 and Area D=5x/8
A:C:D
=3x:3x/8:5x/8
=24x:3x:5x
=24:3:5

(b)D:the whole pizza
=5x/8:8x
=5x:64x
=5:64

1. a/b=b/c=4-----32/8=8/2=4------a=32 b=8 c=2
2.(a)A:C:D=24:15:25
(b)D:the whole pizza 25:64

2008-01-02 23:20:43 補充：
2. （a ） B佔整個pizza 5/8，再要將 5 分成 3份和5份，所以要將5x3和5x5。得出結果是15:25,而15+25剛好是40所以最大的5份要倍大8倍，那麼5/8就同時倍大8倍變成40/64，3/8也倍8倍變成24/68。列式計算如下：5/8=5x(3+5)/8x(3+5)=40/64C=3x5/64=15/64D=5x5/64=25/64A=3/8=24/64所以A:C:D=24:15:252.（b）25/64 是合理的。

2008-01-02 23:29:32 補充：
奇怪：我第一次答題中2(a)A:C:D=24:15:25後面不知為甚麼會多了&nbsp幾個怪字，那幾個是沒有意義的。應該只是2.(a)A:C:D=24:15:25