机经讨论（三）

tongxun

首先感谢G友JSC的无私奉献！ 欢迎大家跟帖讨论： 1、A 完成500各工作量用3小时，B完成500用6小时，C完成500用5小时，三个人共同完成1000用多少小时？ ----------- 20/7 ====== 2、xx（具体数）个筐篮子装苹果，每筐数量不同，问median的数量。 (1)20%的筐里的多于**个 (2)90个筐里的少于24个 ------- E ========= 3、Are m and n all to the left of 0 on 数轴？ (1)m+n<0 (2)m*n>0 ------------ C 因为：条件1）只知道M与N 之间有两种情况：M、N同为负数、M与N 一正一负，且负数绝对值大。条件2）只知道M、N同号。1）+2） 可知同在数轴的左侧。 ========= 4、what's the value of r? (1)|r-1|=|r-3| (2)|r-4|=2 A 因为：解开1）可得R=2。解开2）R可为2、6。 =========== 5、12 people donate a total of A dollars, but later, x people said that they won't donate, how many additional dollars should the remaining people donate? ？ --------- 6、what is the sum of the odd numbers between -51 and 57, inclusively? 53+55+57 =========== 7、An ink is a mix of four inks of different colors, red:blue:green:yellow=6：5：2：3(后面两个数不准）,how many litres of green ink in a certain mix ink? (1)red比blue多2 litres. (2)mix ink 一共**(一具体数）litres ----------------- D ======= 8、XX 在royalties上赚了$3million,and 在sale上赚了$20million.之后又在sale上赚了$108million,在royalties上赚了$90million.what's the ratio of royalties to sales declined? --------- -147% ======= 9、100 kilos fresh fruit,99% is water. After dried, 98% is water, if the weight of fruit didn't change, what's the total weight of the dried fruit? [50](注意后面只写了fruit，没写fresh fruit，fruit的意思是干水果，而问题问的是干燥后的 “水加干水果”的总重） ---------- 100-99=1； X-1/X =O.98 ；X=50 =============== 以上纯个人意见，请大家跟帖讨论！

hahabear

5. x*A/12
6. wrong question?
8. what is the meaning of this ratio?
9. I don't know the question.

tongxun

5、你的算法是在每人捐款相等的基础上的出的。如果不相等，怎么算？
6、It is not a wrong question。
8、比率
9、100克的鲜水果，99%的水。晒干后，含水98%，问此时此水果的重量。

hahabear

6. O, yes, interesting math game! I got it.
7. 不知道，这个比率是谁比谁？ sales declined？

tongxun

7、题目应该欠清楚。但按一般的数学来讲，应该是现在比过去的。

cook

9、100 kilos fresh fruit,99% is water. After dried, 98% is water, if the weight of fruit didn't change, what's the total weight of the dried fruit? [50](注意后面只写了fruit，没写fresh fruit，fruit的意思是干水果，而问题问的是干燥后的 “水加干水果”的总重）
----------
100-99=1； X-1/X =O.98 ；X=50
===============
Answer: 50
R: "if the weight of fruit didn't change" --> 100*(1-99%)/(1-98%)=50

tongxun

It is another good resolution, I think. The answer exactly is 50.