prep-1-10,11,12,16

10. 719-!-item-!-187;#058&000515 Of the 800 students at a certain college, 250 students live on campus and are more than 20 years old. How many of the 800 students live on campus and are 20 years old or less?

 (1) 640 students at the college are more than 20 years old.

(2) 60 students at the college are 20 years old or less and live off campus.

答案选C,我选B,为什么是C?

11. 959-!-item-!-187;#058&000583 If p is a positive odd integer, what is the remainder when p is divided by 4 ?

 (1) When p is divided by 8, the remainder is 5.

(2) p is the sum of the squares of two positive integers.

答案选D,请问2是点算出来的?

12. 1013-!-item-!-187;#058&000609 Of the 25 cars sold at a certain dealership yesterday, some had automatic transmission and some had antilock brakes. How many of the cars had automatic transmission but not antilock brakes?

(1) All of the cars that had antilock brakes also had automatic transmission.

(2) 2 of the cars had neither automatic transmission nor antilock brakes.

答案选e，我选A，这样可以直接得出是0，点解我错了。

16. 1275-!-item-!-187;#058&000656 Lines n and p lie in the xy-plane. Is the slope of line n less than the slope of line p ?

 (1) Lines n and p intersect at the point (5,1).

(2) The y-intercept of line n is greater than the y-intercept of line p.

答案选C，个人觉得SLOPE可以是正负，所以答案无法确定选E，点解我又错了？

问题有点多，谢谢解答。

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