求助两道数学题

michaelzhao007UID: 2195708

If a and b are intergers such that a+b<1000 and A/B=0.625.what is the greatest possible value of b?
答案是６０８，我怎么算都是６１５．求助高人啊．
, U- r' G3 t& q+ Z

How amy positive intergers less than 1000 are mutiples of 5 and are equal to 3 times an even interger?

amyceresUID: 2206721

615*0.625不是整数啊，a b都是整数
$ I% X$ u) G/ c4 X! p% _9 s第二道我觉得应该是30 60 90 120 150……990

einsteiniiUID: 2252184

板凳

suimongUID: 2256015

原帖由 amyceres 于 2006-10-5 20:50 发表
, I; d2 o$ Z) F" s* a4 |615*0.625不是整数啊，a b都是整数
第二道我觉得应该是30 60 90 120 150……990

同意。

powerpycUID: 2180236

老实说,第2题没看懂,那个"are equal to 3 times an even interger"是什么意思哟

qiuwanyingUID: 2198063

原帖由 powerpyc 于 2006-10-6 18:54 发表
- L+ R, l5 X3 Q" Z老实说,第2题没看懂,那个"are equal to 3 times an even interger"是什么意思哟

$ ]9 x, v  i; _, g+ Z% @5 @; m) G. D“等于3乘以一个偶数”

michaelzhao007UID: 2195708

第2题答案是33个.很纳闷啊..

amyceresUID: 2206721

are equal to 3 times an even interger你理解成是3的倍数的一个偶数就可以解决了

water0915UID: 2222422

1.If a and b are intergers such that a+b<1000 and A/B=0.625.what is the greatest possible value of b?

1.625x<1000
3 O! w2 Z/ k* X$ j1 H3 D; }7 Mx<615.358

, j% {9 o7 G+ u" b/ f+ }* o0.625 = 5/8
) x; ]# j' l+ b
x= multiple of 8

count down 615 to find the nearest multiple of 8, then we got 608
1 z  U) C+ }1 b1 @0 [

8 k6 o% b/ d" }2.How amy positive intergers less than 1000 are mutiples of 5 and are equal to 3 times an even interger?
3 J' U5 y( W8 t. H. z9 W/ i: N
even no. = 2x

* ]5 y; V7 Y$ e% a! O& A3*(2x)=6x
* m# e( N: ]; q
nos are multiple of 6 and 5 which is 30.

# b) ]/ w) r( x3 s1000/30 = 33