DS Form15 sec 1-5,sec1-21,sec1- 25

[vera1010]

5. what is the greatest interger that is less than X?

(1) X=9/4

(2)X=(-3/2)^2

ANS:D

看不懂

21. Is X>1?

(1) X > 0

(2)1/X < 1

ANS:C

我的答案是B

25.Exactly 3 deposits have been made in a savings account and the amounts of the deposits are 3 consective integer multiples of 7.
If the sum of the deposits is between $120 and $170.what is the amount of each the deposit?

(1)The amount of one of the deposits is $49

(2)The amount of one of the deposits is $63

ANS:B
我的答案是C

麻煩大家了,感激不盡!!!

[dibert8]

5.
(1) 小於 9/4 的最大整數 = 2
(2) = 9/4
=> (D)

21.
(1) 不一定
(2) if X > 0 then X >1, or X < 0
(1) & (2) => X >1
=> (C)

25.
設 3 數 = 7*(n-1), 7*n, 7*(n+1)
120 < 3*7n < 170, n = 6, 7, 8
3 數 = 35, 42, 49 (n = 6) ; 42, 49, 56 (n = 7) ; 49, 56, 63 (n = 8)
(1) n = 6, 7, 8
(2) n = 8 (唯一解)
=> (B)