已知某商品流通企业前20个周期的
=76，
=68，取N＝5，则用二次移动平均数法预测第25周期的销售量为（）。
A．99
B．89
C．110
D．104
参考答案：D
解析：
at=2Mt(1)-Mt(2)-2×76-68=84；
bt=2/(N-1)(Mt(1)-Mt(2))-1/2×8=4；
Yt+T=at+bt×T＝84+4×5＝104。
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| Early one morning, an old woman was carrying a big basket of cabbages on her head to the market, She hoped to 1 them to the people from town. The mountain road was narrow and the old woman was walking 2 , because she did not want to have 3 and lose her cabbages. Suddenly she 4 a loud bell and a bicycle came round the corner. It passed her and went very fast 5 the hill. The old woman had to jump to one side of the 6 so quickly that the basket of cabbages nearly fell into the valley(山谷). She looked up, and saw that a young boy was on the bicycle. He was 7 on without even looking round to see 8 the old woman was all right. The old woman began to shout,"Come back, young man!You dropped something! " When he heard this, the boy stopped the bicycle so suddenly that he 9 fell off. Then he turned and began to 10 the bicycle back up to the hill. "What is it?"he asked. "What did I drop?" " Little boy, " the old woman answered, " you dropped your manners (礼貌) . " | ||||
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