GWDT1数学，请教！

际遇2011 · 发表于 2013-8-4 09:36:36

Q30:

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.
该题答案是D。个人觉得是A。

Q23:

In the xy-plane, point (r, s) lies on a circle with center at the origin. What is the value of r2 + s2?

(1) The circle has radius 2.

(2) The point (√2, -√2) lies on the circle.

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.

该题答案是D。想请教算法！
先行感谢各位大神指点！

Bunnymin1217 · 发表于 2013-8-4 10:20:42

不是大神！
Q 30 题是A 你可以查 gmatclub。com 或beatthegmat。com 他们都有很好的解释。那道题应该是og 12上的。

Q23 这个是那个beatthegmat网站贴过来的这道题是og 2nd edition 上的。

Just remember the basic formula of the coordinate geometry.

Distance between two points (x1,y1) and (x2,y2) is= sqroot ((x2-x1)2 +(y2-y1)2)

Given: x1,y1 = r,s; x2,y2= 0,0 (since origin)

Now
St 1: radius is 2, i.e. sqroot ((r^2-0)+(s^2-0))=2 -> r2+s2=4 -- suff
St 2: (Sqroot(2), -sqroot(2)) --> sqroot (sqroot(2)^2-0 + (-sqroot(2)^2) = sqroot(4)= 2 distance hence we can again find r^2 +s^2 -- suff
＝＝》D
画个图就很清楚了。 statment 2 就是先求出来圆的半径，就能用勾股定理求出来要的值了！
希望解释的比较清楚！

Rita22246 · 发表于 2013-8-4 10:33:27

我也觉得是 A。。。答案错了吧。。那个第二个条件。。有无数种可能诶==

际遇2011 · 发表于 2013-8-4 11:18:41

Bunnymin1217 发表于 2013-8-4 10:20
不是大神！
Q 30 题是A 你可以查 gmatclub。com 或beatthegmat。com 他们都有很好的解释。那道题应该是og 1 ...

超级感谢！！！膜拜大神！

际遇2011 · 发表于 2013-8-4 11:19:41

Rita22246 发表于 2013-8-4 10:33
我也觉得是 A。。。答案错了吧。。那个第二个条件。。有无数种可能诶==

灰常感谢！我觉得楼上说的也很有道理~~同参考之

GWDT1数学，请教！

所属分类: GMAT考试

正在浏览此版块的会员 ()

浏览过的版块