[讨论]做题做晕了的和依然清醒的高手们指点指点

KsWonder

做题做的把基础概念都混淆了。请大家帮忙理顺一下，麻烦

(1)能否把1视作某个数的factor?
(2)0是否devisable by all numbers(except 0)?

(3)462-!-item-!-187;#058&000279
One
kilogram of a certain coffee blend consists of x kilogram of type I
coffee and y kilogram of type II coffee. The cost of the blend is C
dollars per kilogram, where C = 6.5x + 8.5y. Is x < 0.8 ?
(1) y > 0.15
(2) C >=7.30
answer:B 我认为应该选E

4）7589-!-item-!-187;#058&005492
 If x and y are positive integers such that x = 8y + 12, what is the greatest common divisor of x and y ?
(1) x = 12u, where u is an integer.
(2) y = 12z, where z is an integer.
answer:C 答案我同意，但是the greatest common divisor是不是12？

（5）14175-!-item-!-187;#058&010326
 If the drama club and music club are combined, what percent of the combined membership will be male?
(1) Of the 16 members of the drama club, 15 are male.
(2) Of the 20 members of the music club, 10 are male
answer:E. 是否应该考虑drama and music club的member有重合，否则不就应该是(15+10)/(16+20).