Last month, there were 30 male students and 20 female students in the chess class. The number of male students decrease by r% and the number of female students increase by r% in this month. If the number of male and female students are the same in this month, find r.
Thanks!
Maths Question
2007-07-21 2:08 am
回答 (2)
2007-07-21 2:17 am
✔ 最佳答案
30*(1-r%) = 20*(1+r%)30-30r% = 20+20r%
10-30r% = 20r%
10 = 20r%+30r%
10 =50r%
10/50 =r%
r =1/5
r =20%
2007-07-20 18:21:42 補充：
check ANS.male會係30*(1-r)→30*(1-20%)=24female會係20*(1 r)→20*(1 20%)=24
2007-07-20 18:23:34 補充：
因為條題目話male and female students are the same in this month所以male 同 female 都係24
2007-07-21 2:15 am
(30+20) = 30 x (1-r) + 20 x (1+r)
50 = 30-30r+20+20r
50 = 50-10r
50+10r = 50
10r = 0
r = 0
50 = 30-30r+20+20r
50 = 50-10r
50+10r = 50
10r = 0
r = 0
收錄日期: 2021-05-01 23:05:55
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070720000051KK03467