问题标题:
【一道英文数学题=Therearefivenumbers.Theiraverageisnine.Ifwechangeonenumbertoone,andanothernumbertotwo,theaveragebecomeseight.Ifwerechangethesetwonumbers:onenumbertotwotimesasmanyasitsoriginalvalue,andtheothe】
问题描述:
一道英文数学题=
Therearefivenumbers.Theiraverageisnine.Ifwechangeonenumbertoone,andanothernumbertotwo,theaveragebecomeseight.Ifwerechangethesetwonumbers:onenumbertotwotimesasmanyasitsoriginalvalue,andtheothertofourtimesasitsoriginalvalue,theaverageofthefivenumberswillbecomethirteen.Whichtwonumbershavebeenchanged?
孔波回答:
设Therearefivenumbers为ABCDE
则A+B+C+D+E=5*9=45
1+2+C+D+E=5*8=40
2A+4B+C+D+E=13*5=65
解得A=2
B=6
即6and2twonumbershavebeenchanged
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