Angus goes to one of two coffee shops in his home town. He goes to Tarbucks 70 %
ID: 3021896 • Letter: A
Question
Angus goes to one of two coffee shops in his home town. He goes to Tarbucks 70 % of the time and otherwise goes to Costly Coffee. Either way, he buys a latte 68 % of the time, regardless of which place he chose.
Part a)
You are told that Angus went into town for a coffee today. What is the probability (to 3 d.p.) that he had a latte at Tarbucks?
Part b)
Define two events as follows:
L = Angus had a latte
T = Angus went to Tarbucks
Are the two events independent?
A. No
B. Yes
Part c)
Given that Angus had a latte in town, what is the probability (to 3 d.p.) that he drank at Costly Coffee?
Part d)
What is the probability (to 3 d.p.) that Angus went to Tarbucks or had a latte or both?
Explanation / Answer
Let
T = tarbucks
C= costly coffee
L = latte
a)
P(L n T) = P(T) P(L|T) = 0.70*0.68 = 0.476 [ANSWER]
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b)
A: YES.
This is because he buys a latte 68% of the time regardless of coffee house.
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c)
As drinking latte is independent of coffe house, then
P(C|L) = P(C) = 0.30 [ANSWER]
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d)
P(T U L) = P(T) + P(L) - P(T) P(L|T)
= 0.70 + 0.68 - 0.70*0.68
= 0.904 [ANSWER]