課程名稱︰微積分乙下
課程性質︰系必修
課程教師︰王振男
開課學院：醫學院
開課系所︰醫學系
考試日期（年月日）︰2013/5/21
考試時限（分鐘）：30分鐘
是否需發放獎勵金：是，謝謝
（如未明確表示，則不予發放）
試題：
1.（10％）A bin contains 3 different types of disposable flashlights. The
probability the a type 1 flashlight will give over 100 hours of use
is 0.7, with the corresponding probabilties for type 2 and type 3
flashlights being 0.4, 0.3, respectively. Suppose that 20％ of the
flashlights in the bin are type 1, 30％ are type 2, and 50％ are
type 3.
(a) What is the probability that a randomly chosen flashlight will give
more than 100 hours of use？
(b) Given the flashlight lasted for over 100 hours, what is the
conditional probability that it was a type j flashlight, j＝1,2,3.
2.（10％）Consider 3 urns. Urn Ａ contains 2 white and 5 red balls; urn Ｂ
contains 6 white and 4 red balls; and urn Ｃ contains 1 white and 6
red balls. If 1 ball is selected from each urn, what is the
probabilty that the ball chosen from urn Ａ was white, given that
exactly 2 white balls were selected？
答案：
1.(a) 0.41
(b) j＝1：14/41；j＝2：12/41；j＝3：15/41
2.8/11
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