pp-T1-DS114

[Huang Hsin-Yi]

114.
Henry purchased 3 items during a sale. He received a 20 percent discount off the regular price of the most expensive item and a 10 percent discount off the regular price of each of the other 2 items. Was the total amount of the 3 discounts greater than 15 percent of the sum of the regular prices of the 3 items?

(1) The regular price of the most expensive item was $50, and the regular price of the next most expensive item was $20.

(2) The regular price of the least expensive item was $15.

Ans: A

好奇怪 在A選項 三個item只知兩個價格 要如何求出discount

[puja]

114.
Henry purchased 3 items during a sale. He received a 20 percent discount off the regular price of the most expensive item and a 10 percent discount off the regular price of each of the other 2 items. Was the total amount of the 3 discounts greater than 15 percent of the sum of the regular prices of the 3 items?

(1) The regular price of the most expensive item was $50, and the regular price of the next most expensive item was $20.

(2) The regular price of the least expensive item was $15.

Ans: A

好奇怪 在A選項 三個item只知兩個價格 要如何求出discount

the regular price 應該是指一個標準的固定價格,也就是說有一個標準固定價格打20%折扣,然後打10%的折扣也有它一個標準價格~~

[Huang Hsin-Yi]

還是看不太懂PUJA大大的說明
能不能舉例說明

[小花]

50*0.2=10------最高價的折扣
20*0.1=2-------次高價的折扣
設最低價賣X元
題目問總折扣是否大於15%
10+2+0.1X/50+20+X>15%
求得 30>X (X小於30時折扣會大於15%)

(1)告訴我們次低價20 最低價必小於30
條件充足
(2) 只有最低價的資訊 條件不足

[Huang Hsin-Yi]

喔 小花 你真是我的救命恩人 太感謝了!!

[chencraig0227]

50*0.2=10------最高價的折扣
20*0.1=2-------次高價的折扣
設最低價賣X元
題目問總折扣是否大於15%
10+2+0.1X/50+20+X>15%
求得 30>X (X小於30時折扣會大於15%)

(1)告訴我們次低價20 最低價必小於30
條件充足
(2) 只有最低價的資訊 條件不足

....我算出來是X<150....不太一樣! 不過一樣是充分!

[sandrine]

我覺得不是這樣算耶
我先設 3items 便宜A B C貴
題目是問總價錢個別三個items折扣是否有比全部一起折扣的多
列式是0.9A+0.9B+o.8C>(A+B+C)0.75???
條件一:
0.9A+18+40>0.75A+15+37.5
這樣看的話 前式一定大於後式 條件充足

條件二:
13.5+0.9B+o.8C>11.25+0.75B+o.85C
這樣因為B和C不確定 所以無法構成充分條件
答案才是A吧 (不知有沒有算錯...)