P2-DS-70

[小花]

70. 6564-!-item-!-187;#058&004850
If eleven consecutive integers are listed from least to greatest, what is the average (arithmetic mean) of the eleven integers?

(1) The average of the first nine integers is 7.

(2) The average of the last nine integers is 9.

Ans:D


想請教一下 eleven consecutive integers 所以我麼知道 等差=1
是嗎?

[nemolee]

70. 6564-!-item-!-187;#058&004850
If eleven consecutive integers are listed from least to greatest, what is the average (arithmetic mean) of the eleven integers?

(1) The average of the first nine integers is 7.

(2) The average of the last nine integers is 9.

Ans:D


想請教一下 eleven consecutive integers 所以我麼知道 等差=1
是嗎?

題目要的是整數要連續 11個，例如從1,2,3....數到11，或例如從3,4,5,6....13，自然而然這些連續整數都差1..
所以重心應該不是在等差=1這個地方

[小花]

是這樣連續嗎?
2, 3,4,5 ...

[nemolee]

ya...