大家好～
不好意思我當時在做這個題目時
真心覺得是簡單的題目
但是被改出來卻沒有拿到半點分數@@
加上老師奇怪的堅持不公佈答案
我只好po上自己的答案並來向大家請益
題目是英文 但很好理解的
先謝謝大家了
A manufacturing plant has 3 different machines denoted M1, M2 and M3; 20%,
35% and 45% of the production comes from machines M1, M2 and M3,
respectively; 3% of the production from M1 is defective, 2% of the production
from M2 is defective and 1% of the production from M3 is defective, all at
random.
a. Calculate the percent of defective items from the entire manufacturing
plant.
b. A truck load of items is brought to a quality control clerk who randomly
selects one item and finds it to be defective. What is the probability that
this item was manufactured by machine M2?
我的答案是
a.1.8% (0.018)
b.0.02 (2%)
我的想法就是設定全部products是S
M1 0.20S
M2 0.35S
M3 0.45S
而其中有缺陷的 就用M1:0.2S^（缺陷的比例）
所以a小題的答案我就會用所有的有缺陷的比例去除以S
這樣做錯了嗎？
老實說很訝異我沒有拿到這題分數:(
請大家不吝指點小魯～
謝謝！
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