题库搜索>问题求解PS-12224
Running at their respective constant rates, machine X takes 2 days longer to produce w widgets than machine Y. At these rates, if the two machines together produce 5/4 w widgets in 3 days, how many days would it take machine X alone to produce 2w widgets?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
我有更好的解析 
暂无雷哥网文字解析
设machine Y在d天生产w widgets所以X 生产同样的数量要用d+2天，在一天中，Y生产w/d and X生产w/(d+2)widgets
同时工作他们可以生产w/d + w/(d+2) = [2w(d+1)]/[d(d+2)] widgets
三天可以生产3*[2w(d+1)]/[d(d+2)] = 5w/4, 得到d =4,x生产w widgets用时4+2 = 6天,所以生产2w用时2*6=12天
小良冠二郎
選擇題，那當然適用代數法
0
0
回复
2023-02-09 14:48:44
GMAC是猪猪回复小良冠二郎
我傻了，果然这个聪明
0
0
回复
2023-03-15 00:44:59
rhetoric
设生产速率分别为xy w/x-w/y=2 3(x+y)=5/4*w 求2w/x w约去联立上面的俩式子求解即可
0
0
回复
2022-11-12 16:48:08
追梦的猪猪
产量和时间成正比，所以两个机器一起干的话： (5w/4)/2w=3天/x天，所以俩一起干的时间 x 是 24/5，大概是将近 5 天吧 但是 x 干的慢，如果它自己干，肯定大于 2*24/5，也就是大于 9.6 天。 做一个 w，x 都比 y 慢两天，别说两个 w，所以不可能是 10 天就干完的，肯定更多，所以 --> 12
0
0
回复
2021-11-04 14:40:44
689665sn
直接代入选项：X单独做2w个的时间是4 6 8 10 12，那x单独做W个的时间是2 3 4 5 6，题干给出x做w个比y做w个慢两天，则y单独做w个为0 1 2 3 4天。根据产量/速度=时间，得5/4w/[w/d+w/(d+2)]=3，化简代入1 2 3 4即可
0
1
回复
2021-10-04 09:56:45
174634p
我算半天没算出来但是带选项进去就很快
2
0
回复
2021-09-29 17:19:45
Cheryl
假设y生产w需要y天，那么x生产w就需要y+2天，根据后面一起生产的列方程： （1/（y+2)+1/y)*3=5/4，解得y=4，y+2=6，说明x生产w需要6天，那么生产2w就需要12天
1
0
回复
2020-12-01 14:07:17
TOBEAWESOME
好家伙，列式子之前观察一下，给出的产量都是w的倍数，最后问的也是2w时Y花费的时间，所以列式子的时候如果是按照时间*生产速度=产量，那么所有的w就可以约掉。同时设时间而非速度为未知数可以简化。设Y设备生产w的时间为y天，那么生产2w的时间自然是2y。不要看到条件给出了多2天，就想列成产量/速度=时间。
1
0
回复
2020-11-19 22:12:43
ALLAN FERRARA
计算错误导致我在这道题上浪费了十几分钟的时间，气死我了
5
0
回复
2020-10-02 18:29:38
亲亲的清清HQQ
求助，w怎么被约掉了？
0
0
回复
2019-09-17 20:40:40
糖糖要加油
算到最后忘了乘以2.。。。
1
0
回复
2018-01-12 19:00:12
默默回复糖糖要加油
效率的相加减
0
0
回复
2018-04-28 06:53:21
默默回复糖糖要加油
求的过程中，W会被约掉
0
0
回复
2018-05-04 05:51:44
July770
这里x比y长两天，也就是y=x-2，在做题时把大小搞反了，所以做错了。 具体等式为：求2x=? 已知： y=x-2; 3*(1/x+1/y)=5/4; 联立求解得x=6,2x=12,证毕！
2
0
回复
2017-11-06 16:02:46
科目：
问题求解PS
来源：
GWD
题目信息7m26s
平均耗时
57%
平均正确率
该题由网友iw2tglH提供
点击上传问题求解PS -17755
Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 10?
问题求解PS -17752
Which of the following describes the set of all possible values of the positive integer k such that, for each positve odd integer n, the value of nk is midway between consecutive integers？
问题求解PS -17741
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?
问题求解PS -16762
【OG20-P150-27题】Set X consists of eight consecutive integers. Set Y consists of all the integers that result from adding 4 to each of the integers in set X and all the integers that result from subtracting 4 from each of the integers in set X. How many more integers are there in set Y tha...
问题求解PS -15114
The sum of the first n positive perfect squares, where n is a positive integer, is given by the formula n33 +cn2 +n6 , where c is a constant. What is the sum of the first 15 positive perfect squares?
问题求解PS -17755
Each of the integers from 0 to 9, inclusive, is written on a separate slip of blank paper and the ten slips are dropped into a hat. If the slips are then drawn one at a time without replacement, how many must be drawn to ensure that the numbers on two of the slips drawn will have a sum of 10?
问题求解PS -17752
Which of the following describes the set of all possible values of the positive integer k such that, for each positve odd integer n, the value of nk is midway between consecutive integers？
问题求解PS -17741
The sum of the first 100 positive integers is 5,050. What is the sum of the first 200 positive integers?
问题求解PS -16762
【OG20-P150-27题】Set X consists of eight consecutive integers. Set Y consists of all the integers that result from adding 4 to each of the integers in set X and all the integers that result from subtracting 4 from each of the integers in set X. How many more integers are there in set Y tha...
问题求解PS -15114
The sum of the first n positive perfect squares, where n is a positive integer, is given by the formula n33 +cn2 +n6 , where c is a constant. What is the sum of the first 15 positive perfect squares?
分享
周末、晚班滚动开班 
24+35+35+6课时 
