[問題] GWD5-Q21

[kwtluck]

Q21:
Theater M has 25 rows with 27 seats in each row. How many of the seats were occupied during a certain show?
(1)During the show, there was an average (arithmetic mean) of 10 unoccupied seats per row for the front 20 rows.
(2)During the show, there was an average (arithmetic mean) of 20 unoccupied seats per row for the back 15 rows.

Answer:E

答案不是"C" 請教各位大大!!Thanks~~

[spreewell]

(1)你只能確定前20排，平均每排有10個空位，但後面5排的情形無法確
定，所以不充分。
(2)你只能確定後15排，平均每排有20個空位，但前面10排的情形無法確
定，所以不充分。
合併(1)+(2)因為兩者都是平均數，你無法確認重疊的部份跟非重疊部分座位的空缺情形，所以仍不充分

如果條件改成給你前20排的平均空位及後五排的平均空位，或是後15排的空位情形及前十排的空位情形即可求出答案。

[kwtluck]

怎麼會忽略呢? 我真是笨呀~~ 我是豬...豬...豬....
**仍然是spreewell大大鼎力相助!!**