11月3日南京初战，做prep数学中遇到很多难题，跪求大师指点，能帮我详解下吗。

kelly周 · 发表于 2011-10-12 15:37:29

1.Working alone at its own constant rake,a machine seals k cartons in 8h and working alone at its own constant rake,a second machine seals k cartons in 4 hours.If the two machine,each working at its own constant rake and for the same period of time,together sealed a certain number of cartons.What percent of the cartons were sealed by the machine working at the faster rate?
答案：66 2/3%

2.If m is a postive odd mteger between 2 and 30,then m is divesible by how many different postive prime numbers?
(1)m is not divisible by 3
(2)m is not divisible by 5

3.The lifetimes of all the batteries produced by a certain company in a year have a distribution that is symmetric about the mean m.If the distribution has a standand deviation of d,what percent of the distribution is greater than m+d?
(1)68% of the distribution lies in the inerval from m-d to m+d ,inclusive
(2)16% of the distribution is less than m-d
答案：each is sufficient

mlhxzfq · 发表于 2011-10-12 16:24:11

第二题答案是多少啊

kelly周 · 发表于 2011-10-13 15:16:20

(1)is sufficient,(2)is not sufficient

11月3日南京初战，做prep数学中遇到很多难题，跪求大师指点，能帮我详解下吗。

所属分类: GMAT考试

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