hehe,GWD求解

GWD1--Q29

June25,1982,fell on a Friday. On which day of the week did June 25,1987,fall?(Note:1984 was a leap year)

A.Sunday

B.Monday

C.Tuesday

D.Wednesday

E.Thursday

答案是选D，可是我觉得是选E

GWD12--Q11

THe product of the units digit,the tens digit,and the hundreds digit of the positive integer m is 96.What is hte units digit of m?

(1)m is odd

(2)The hundreds digit of m is 8

答案是A

Q16

If m,p and t are posotive integers and m<p<t, is the product mpt an even integer?

(1)t-p=p-m

(2）t-m=16

答案是选E，可是我认为是选A

Q30

M=(-6,-5,-4,-3,-2)

T=(-2,-1,0,1,2,3)

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above,what is the posibility that the product of the two integers will be negative?

A.0

B1/3

C.2/5

D1/2

E3/5

我认为答案是选     E，可是答案是选D

请问哪位大牛可以帮忙解答，谢啦

GWD1--Q29

June25,1982,fell on a Friday. On which day of the week did June 25,1987,fall?(Note:1984 was a leap year)

解:从1982-1987,共五年,合计365 X 4 + 366 (1984是闰年)=1826天

1826天/7天=260个星期零6天, 所以就是星期五再往后数六天,星期四.

GWD12--Q11

THe product of the units digit,the tens digit,and the hundreds digit of the positive integer m is 96.What is hte units digit of m? (1)m is odd; (2)The hundreds digit of m is 8

解:设M的百位,十位及个位分别为A,B,C (隐藏条件A,B,C小于等于9,且A,B,C不等于0)

则M=100A+10B+C, ABC=96.

条件(1),M为奇数,所以推出C亦为奇数. 因为能被96整除的奇数有1,3; C不能为1,如果C=1,则AB=96是不可能的.所以C=3.充分.

条件(2),百位数A=8, BC=12,可以是C=3,4,2,6; 不充分.

Q16

If m,p and t are posotive integers and m<p<t, is the product mpt an even integer?

(1)t-p=p-m

(2）t-m=16

解:

条件(1)推出T+M=2P, 即T+M是偶数(T和M可以同为奇,也可以同为偶),但P可以是偶数也可以是奇数,三数相乘,不能定奇偶;不充分;

条件(2),T和M可同为奇,同为偶,但P不一定是奇还是偶,不充分.

所以E.

我是这么认为的哦，不知对不对。。

一  二  三  四  五  六  日

               6.25 26  27

28  29  30  1

一周是从1982年的6.25Fri到下一周的7.1Thur，当260个周过去以后，得从周五开始数6天，所以将是下周的Wed 

Q30

M=(-6,-5,-4,-3,-2)

T=(-2,-1,0,1,2,3)

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T above,what is the posibility that the product of the two integers will be negative?

A.0; B1/3; C.2/5; D1/2; E3/5

解: M中全为负值,所以要使MT为负,须在T中选取非负值,只有1,2,3可选, 所以 (C51C31)/(C51C61)=1/2,D. 留意, 0不是负数也不是正数.