Maths
2009-09-24 7:04 am
In a competition,20 marks were given for each correct answer ,10 marks were deducted for each wrong answer ,and 5 marks wew deducted for each question given up.Jimmy answered 3 questions correctly ,5questions wrongly ,and gave up the rest .If Jimmy got 0 marks at the end, how many questions were provided for him in the competition?
回答 (3)
2009-09-24 7:49 am
✔ 最佳答案
Let there are x questions :Jimmy gave up x - 3 - 5 = x - 8 questions
The marks of Jimmy is 3 * 20 - 5 * 10 - (x - 8) * 5 = 0
60 - 50 - 5x + 40 = 0
5x = 50
x = 10
10 questions were provided for him in the competition.
2009-09-24 01:35:52 補充：
唔用方程式都得,
對 3 題有 3*20 = 60分
錯 5 題扣了 5*10 = 50分
所以對 3 題 錯 5 題有 60 - 50 = 10分
由於 Jimmy 只有 0 分, 因此這 10分是因 give up 題目而被扣除,
give up 一題扣 5 分, 所以 Jimmy give up 了 10/5 = 2 題
所以總題數 = 3 + 5 + 2 = 10題
2009-09-25 7:43 am
2009-09-24 8:18 am
你可唔可以唔好用方程式啊？？
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https://hk.answers.yahoo.com/question/index?qid=20090923000051KK01952