一道英语奥数题there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days
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一道英语奥数题there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days
一道英语奥数题
there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days did B and C work together?
一道英语奥数题there is a road to be repaired.A needs 10days to finish,B needs 12days and C needs 15days .Now they work together to mend the road.A left halfway,in the end ,they spent 6days finishing the road.After A left,find out how many days
有一个被修复的道路.A需要10天完成,B需要十二天和C需要15天.现在他们一起工作,修补道路.A中途离场,最后,他们花了6天完成了道路.A离开后,求有多少天B和C一起工作?
列个方程,很简单的.
设A工作x天,总工作量为1
可得:
(1/10 + 1/12 + 1/15)x +(1/12 + 1/15)(6-x)=1
解得 x=1
所以BC一起工作5天
1天
修路,A需要10天,B需要12天,C需要15天。现在三人一起修。A修到中途离开,他们总共用了六天,A离开后,B和C又修了几天?
取一个公倍数120,则A效率为12,B效率为10,C效率为8。到一半时,所用时间为120/(12+10+8)=4,则B和C又修了2天