PREP 新题 求助

谢谢！万分感谢samanthappa传授解题思路!!!

另还是prep的题，这个题好像见过，但是思路一直不清~~~请高人再指点

60. 4972-!-item-!-187;#058&004074 Does the integer k have a factor p such that 1 < p < k ?

(1) k > 4!

(2) 13! + 2 < k < 13! + 13

再来一题，PREP 192

答案是B，不太明白

Of the 75 houses in a certain community, 48 have a patio.  How many of the houses in the community have a swimming pool?

(1) 38 of the houses in the community have a patio but do not have a swimming pool.

(2) The number of houses in the community that have a patio and a swimming pool is equal to the number of houses in the community that have neither a swimming pool nor a patio.

我的想法：

从题可知有48个有天井，27个没有，说是有天井+泳池=没有天井+泳池的，如果只凭条件2无法知道有多少是天井+泳池 or 没有天井+泳池，可能是27以内的任一数组，所以2不充分，与条件1一起才对！

请大家多多帮忙，看看147和这道题怎么个讲法？ 谢谢！！！

147

let The average (arithmetic mean) salary of the managers = M

    The average (arithmetic mean) salary of the directors = D

    average salary of all employees= A

    percent of the employees on the task force are directors = X

 so, 1.D*X+M*(1-X)=A

     2.D=A+15

     3.M=A-5

subtitute 2 and 3 to 1, gives (A+15)*X+(A-5)*(1-X)=A

                                 AX+15X+A-AX+5X-5=A

            cancelling terms     20X=5

                                   X=25%

                  patio        no patio       total

      pool          x

    no pool                       x

     total         48            27            75 

gives  

                  patio        no patio       total

      pool          x            27-x

    no pool       48-x           x

     total         48            27            75

gives

                  patio        no patio       total

      pool          x            27-x          27

    no pool       48-x           x             48

     total         48            27            75 

B is sufficient

谢谢！万分感谢samanthappa传授解题思路!!!

另还是prep的题，这个题好像见过，但是思路一直不清~~~请高人再指点

60. 4972-!-item-!-187;#058&004074 Does the integer k have a factor p such that 1 < p < k ?

(1) k > 4!

(2) 13! + 2 < k < 13! + 13