3道DS题都错了！！TT GWD-6-2/6/10

citicsbond

Q2:

If every car sold last week at a certain used-car dealership was either a coupe or a sedan, what was the average (arithmetic mean) sale price for all the cars that were sold at the dealership last week?

(1)   The average sale price for the sedans that were sold at the dealership last week was $10,600.

(2)   The average sale price for the coupes that were sold at the dealership last week was $8,400.

                  

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.

the answer is E , however, is it right if we sum two average prices up then divide it by 2 ??

Q6:

If a, b, k, and m are positive integers, is a^k
                    a factor of b^m?

(1)     a is a factor of b.

(2)     k ≤ m

                  

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 is C, anybody could prove it?

Q10:

If each of the students in a certain mathematics class is either a junior or a senior, how many students are in the class?

(1)   If one student is to be chosen at random from the class to attend a conference, the probability that the student chosen will be a senior is 4/7.

(2)     There are 5 more seniors in the class than juniors.

                  

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 is C.

yaoyao99

most of the questions have already been discussed here.

http://forum.chasedream.com/dispbbs.asp?boardID=22&ID=176560&page=1

Please check before you post your questions!

citicsbond

i am stupid,i don't know how to search.

kallyli

你举个例子一辆四轮车十辆轿车用两种方法算一下。答案不同

设b=a*n(n是其他factor),b的m次等于(a*n)的m次方， 等于a的m次*n的m次，k小于m

条件1得出 junior/senior=3/4, (4-3)/7=5/x  可以算出x （x是全体人数）

citicsbond

coupe 是二厢乘用车

sedan 是三厢乘用车

5 coupe * 8400 =42,000

3 sedan * 10600=31800 =>average price is 9225 which is different from 9500,u are right,kallyli.

citicsbond

kallyli,假如你的假设成立，为什么K就<M了呢？

kallyli

这不是假设,是计算过程,你写成数学式子就明白了,我不会写次方,最后写成分母是分子的因子

jingle0915

xiexie