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【OG20-P290-419题】
On the number line above, p, q, r, s, and t are five consecutive even integers in increasing order.What is the average (arithmetic mean) of these five integers?
(1) q + s = 24
(2) The average (arithmetic mean) of q and r is 11.
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1) q+s=24,q,r,s是连续的偶数,则q=10,s=14,那么p,q,r,s,t分别是8,10,12,14,16
2) (q+r)/2=11, 则q=10,r=12, 也能得出p,q,r,s,t
题目讨论 (3条评论)

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TOBEAWESOME
连续偶数,可以看成是公差为2的等差数列。如果一个等差数列的项数是奇数个,那么该数列的平均数等于中位数,并且中位数的值等于它两边任意一对对称的项的平均值,即r=(q+s)/2 =(p+t)/2。所以条件1一看就是可以算出r从而知道数列平均值的,条件2也可以算出r。
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0 回复 2020-10-26 22:32:03
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emily666
five consecutive even integers
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0 回复 2020-05-12 15:11:12
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CB
不考虑负数吗
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0 回复 2019-05-09 17:25:46
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353875zecrn回复CB
根据给的条件1或2,可以确认不是负数
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0 回复 2021-01-19 00:34:24
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