Re: [計量] 一題數學題
※ 引述《ghtmmm (聖艾修伯里)》之銘言：
: In a quality-control test, 50 boxes-each containing 30 machine parts-were
: examined for defective parts. The number of defective parts was recorded for
: each box, and the average (arithmetic mean) of the 50 recorded numbers of
: defective parts per box was 1.12. Only one error was made in recording the 50
: numbers: "1" defective part in a certain box was incorrectly recorded as "10".
: Quantity A
: The actual average number of defective parts per box
: Quantity B
: 0.94
: 答案是C
: 這題看好久還是不知道題目在問甚麼...
大意為：
有50個箱子，每個箱子中有30個機台零件。將這些零件送檢，
得到每個箱子內含缺陷的零件數平均為1.12(個/箱)，
其中有1個缺陷被誤植為10個。
[解]
誤植後的總缺陷數為1.12*50=56(個)。
被誤植的零件其缺陷數多算了9(=10-1)個，所以確切的總缺陷數為56-9=47(個)，
故每箱實際平均缺陷零件數為(47/50)=0.94 --- 亦即為Quantity A。
則Quantity A = Quantity B，
選C。
A2GMAT KH
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※ 編輯: SHAOCHU (180.177.217.26), 05/10/2015 12:54:21
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