A supermarket wants to display VTC coffee by piling them up in layers. The first, second,third and last layers have repectively 20,17,14 and 2 boxes of coffee. Find the number of layers n.
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2008-10-21 9:09 am
回答 (1)
2008-10-21 10:06 am
✔ 最佳答案
The number of boxes in each layer:
20, 17, 14, ......, 2
This is an arithmetic sequence.
a = 20
d = T(n+1) - T(n) = -3
The nth term T(n) = 2
a + (n - 1)d = 2
20 + (n - 1)(-3) = 2
-3(n - 1) = -18
n - 1 = 6
n = 7
Ans: Number of layers is 7.
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收錄日期: 2021-04-23 23:08:40
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081021000051KK00108