额，问个弱智问题，

dadu91418

我觉得是E啊，详情请看6楼～

yongzhe

个人认为条件二下，平均数不一定减少或增加，和条件一一样都不是充分条件，所以支持选C，

SimingGMAT

GMATCLUB 上的解释， 希望有帮助~

The question basically asks whether there will be an increase in total price of those 10 items after the price change.

(1) The five most expensive items each increased in price by 10%. Not sufficient since we know nothing about the other items.
(2) The five least expensive items each decreased in price by 10%. Not sufficient since we know nothing about the other items.

(1)+(2) 10% of the total price of 5 most expensive items is clearly more than 10% of the total price of 5 least expensive items, so overall there will be an increase in total price. Sufficient.

Answer: C.

dadu91418

GMATCLUB 上的解释， 希望有帮助~

The question basically asks whether there will be an increase in total price of those 10 items after the price change.

(1) The five most expensive items each increased in price by 10%. Not sufficient since we know nothing about the other items.
(2) The five least expensive items each decreased in price by 10%. Not sufficient since we know nothing about the other items.

(1)+(2) 10% of the total price of 5 most expensive items is clearly more than 10% of the total price of 5 least expensive items, so overall there will be an increase in total price. Sufficient.

Answer: C.

-- by 会员 SimingGMAT (2012/8/14 3:42:44)

好的，谢谢楼上～彻底懂了～～