请教2题数学， 一题 prep , 一题taotao9

spoiledgirl

41.    3308-!-item-!-187;#058&003278
Last Thursday, John assembled chairs at a rate of 3 chairs per hour for part of the day and Larry assembled no chairs.  Last Friday, Larry assembled chairs at a rate of 4 chairs per hour for part of the day and John assembled no chairs.  If John and Larry assembled chairs for a total of 7 hours during these two days, how many chairs did John assemble last Thursday?

(1)  During these two days, John and Larry assembled a total of 25 chairs.

(2)  During these two days, Larry assembled more chairs than John did.
--------------------------------------------------------------------------------------------------------------------------------------------------------【答案】A
【思路】設John用x小時,Larry用y小時 x+y=7 問x=?
(1)3x+4y=25    ------------------------------------------------------------------- sufficient
(2)4y>3x      ---------------------------------------------------------------------insufficient

这边的小，x, y 是整数么， 为什么条件（2）insufficient 呢？


For any integer k greater than 1, the symbol k* denotes the product of all the fractions of the form  , where t is an integer between 1 and k, inclusive.  What is the value of  ?
答案 1／5，

我算的是1／4，   相问问看， between 1and k 中， 包不包括 1 和k??

syf2233266

第一题，椅子肯定是整数的呀，然后条件就有x=0，y=7或x=1，y=6，或x=2，y=5等几种可能

jessicaddq

41.    3308-!-item-!-187;#058&003278
Last Thursday, John assembled chairs at a rate of 3 chairs per hour for part of the day and Larry assembled no chairs.  Last Friday, Larry assembled chairs at a rate of 4 chairs per hour for part of the day and John assembled no chairs.  If John and Larry assembled chairs for a total of 7 hours during these two days, how many chairs did John assemble last Thursday?

(1)  During these two days, John and Larry assembled a total of 25 chairs.

(2)  During these two days, Larry assembled more chairs than John did.
--------------------------------------------------------------------------------------------------------------------------------------------------------【答案】A
【思路】設John用x小時,Larry用y小時 x+y=7 問x=?
(1)3x+4y=25    ------------------------------------------------------------------- sufficient
(2)4y>3x      ---------------------------------------------------------------------insufficient

这边的小，x, y 是整数么， 为什么条件（2）insufficient 呢？


For any integer k greater than 1, the symbol k* denotes the product of all the fractions of the form  , where t is an integer between 1 and k, inclusive.  What is the value of  ?
答案 1／5，

我算的是1／4，   相问问看， between 1and k 中， 包不包括 1 和k??

-- by 会员 spoiledgirl (2010/3/6 18:41:26)

第二题 “inclusive”表示包括

ellewang81

第一题，椅子肯定是整数的呀，然后条件就有x=0，y=7或x=1，y=6，或x=2，y=5等几种可能

-- by 会员 syf2233266 (2010/3/7 10:36:47)

考虑条件2的时候，是没有椅子数的

spoiledgirl

oo ， 对对， 谢谢楼上的几位，