maths quetion,can anybody help me?

3) These sets of numbers all follow logical patterns. Which numbers replace the question marks?
A) 1,8,?,64,125

1^3, 2^3, ?(i.e.3^3), 4^3, 5^3

? = 3*3*3
=27

B) 9,13,15,? ,21, 25

9, 13, 9+6, ?(i.e. 13+6), 9+2*6, 13+2*6

?=19

C) 00001, 00011, 00101,? 01001

這是16進制以2進制形式的寫法, 但可以先化作10進制, 會較易明白

1*2^0, 1*2^1+1*2^0, 1*2^2+0*2^1+1*2^0, ?, 1*2^3+1*2^0

1, 3, 5, ?, 9

1, 1+2, 1+2*2, ?( i.e.1+3*2), 1+4*2
?=7

轉2進制
7=1*2^2+1*2^1+1*2^0
=111

化回16進制以2進制形式的寫法

?=00111

D) 17,23, ?, 18, 10, 25, 21, 9,15,16

有否寫錯, 數序很亂, 很難找出關連來.

4) Find A,B,C and D,if A+B+C+D=30 AND D=HALF OF B, C=B+3, AND A=B-1.

將 公式內的 A, C, D 與 B 相關起來

A+B+C+D=30
(B-1) + B + (B+3) + 0.5B = 30
3.5B + 2 =30
3.5B=28
7B=56

B=8
A=8-1=7
C=8+3=11
D=0.5*8=4

5) Amta wired her electrical digital clock so that it would run backwards. If she set the clock to the correct time at 16:00, when will the clock next show the correct time?

When the clock run a time interval, for example, t, it will generate a time difference of 2t from the correct time.(i.e. t = 0.5 * time difference) A cycle of a day is 24 hours. The time difference must be 24 hours. Then, t = 12hours (0.5 * 24 hours).

At 04:00, 12 hours backward from16:00, the clock will next show the correct time.

如不明白, 可同時利用兩個時鐘或錶等, 一調前, 一調後, 便能得出結果. 不要只懂得抄.

3B) 19
3C) 00111
4)
　　　A+B+C+D=30
B-1+B+B+3+0.5B=30
3.5B+2=30
　　　　　 3.5B=28
　　　　　　　B=8
A=B-1
=8-1
=7
C=B+3
=8+3
=11
D=0.5B
=0.5(8)
=4
5) 12小時後, 即 翌日的04:00

A) 1,8,?,64,125
1=1^3
8=2^3
64=4^3
125=5^3
so, ?=3^3=27

B) 9,13,15,? ,21, 25
9+6=15
15+6=21
so, ?=13+6=19
19+6=25




only can do these questions~
if i can do the others , i will type later~

2006-10-29 11:35:07 補充：
4) A+B+C+D=30(B-1)+B+(B+3)+B/2=30B-1+B+B+3+B/2=30B+B+B+B/2=30+1-33B+B/2=286B/2+B/2=287B/2=287B=56B=8

2006-10-29 11:36:56 補充：
4)B=8A=8-1=7C=8+3=11D=8/2=4

4)B=8 C=11 D=4 A=7

3) A--27
B--19
5) 打中文 plz

3)00001 , 00011 , 00101, 00111 , 01001
4)(b-1)+b+(b+3)+b/2=30
7b/2=28
B=8, A=7, C=11, D=4