帮忙确认一下12jj中216-219题的答案

alana2003

对，219是d，总是粗心，呵呵

boboll

yes, you are right !
219 is D

CHINAROSE

以下是引用boboll在2003-12-17 23:43:00的发言：
219题里B也可以, (19+23)/2=21
D则是(29+31)/2=30

23和19差4啊

boboll

219题里B也可以, (19+23)/2=21
D则是(29+31)/2=30

CHINAROSE

219是D吧？

CHINAROSE

以下是引用lizaz在2003-12-17 21:57:00的发言：
216题如果都是整数的话，答案B

为啥？

lizaz

216题如果都是整数的话，答案B

dz

呵呵，我马上做一下！久等了！

alana2003

216DS:how many even intergers in a consequence serial of numbers?
(1) there are 34 odd numbers
(2) there are total 68 numbers in a serial of numbers
作者答案及思路：
DZ评价意见：
更新：
我认为e(如果68个数都是整数，则为c)

217 DS: 36 cards, 4 sets, 9 in each set, the cards are marked as 1,2,3,4,5,6,7,8,9
Ask: if one card is taken out, what is unit digit of the sum of the remaining cards?
(1) the unit of the sum of the remaining cards is 6
(2) the sum of the remaining cards is 176
作者答案及思路：
DZ评价意见：
更新：
答案是d吗？好像题目中给了这么多条件没有用上，请指教

218PS: Old JJ 1/2+1/2^2+1/2^3+1/2^3+.......+1/2^10
Ask the range of the sum
作者答案及思路：
DZ评价意见：
更新：
我认为1/2-1

219PS:two prime integars, the difference between them is 2, Ask: which of the following numbers could be the average of the two prime integars.
A. 11 B.21. C 26. D. 30 E.52
作者答案及思路：
DZ评价意见：
更新：
我认为e