涛涛数学 MATH.1 30 31题 请教大牛~

paradisepand

Joanna bought only $0.15 stamps and $0.29 stamps.  How many $0.15 stamps did she buy?
(1)          She bought $4.40 worth of stamps.
(2)          She bought an equal number of $0.15 stamps and $0.29 stamps.
       
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Answer: 这题我选了C 答案是D
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Q31:
A positive integer n is said to be “prime-saturated” if the product of all the different positive prime factors of n is less than the square root of n.  What is the greatest two-digit prime-saturated integer?

A.        99
B.        98
C.        97
D.        96
E.        95

这题我选了D 答案是B。。。。

[此贴子已经被作者于2009-6-6 17:54:25编辑过]

smthbigur

1、 

paradisepand

?~?~?

faster727

1. (1) 0.15x+0.29y=4.40, x and y must be integers. the only answer: x=y=10.(1)is sufficient alone.

   (2) 只知道x=y，不可以求出x和y的值。insufficient。

我觉得答案是A

faster727

第二题给的正确答案也是D呀~ LZ看错了？？

paradisepand

不好意思。。第二题打反了。。

答案是96 我选了98

98=2 7 7

96=2 2 2 2 2 3

不是98吗？~

paradisepand

thx for the 1st q

TASSEL

The second

A.the product of all the different positive prime factors of 99 is 3*11=33>99^1/2

B.the product of all the different positive prime factors of 98 is 2*7=14>98^1/2

C.the product of all the different positive prime factors of 97 is 97>97^1/2

D.the product of all the different positive prime factors of 96 is 2*3=6<96^1/2   Correct

E.the product of all the different positive prime factors of 95 is 5*19>95^1/2

paradisepand

噢 ~~明白了 谢谢！