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probability questions

susumandrai

New member
Joined
Feb 7, 2012
Messages
47
Please tell me if the answers to the following questions are correct.

Problem:
The following types of chocolate are in a box:

Type of Chocolate
Total
Type of Centre
Dark
Milk
White

Soft
12
10
17
39
Hard
18
8
6
32
Total
30
18
23
71

If a chocolate is selected at random, calculate the following probabilities:
a) P(white chocolate)
b) P(soft centre)
c) P(dark chocolate with hard centre)
d) P(soft centre but not dark chocolate)
e) If the chocolate is white, find P(hard centre)
f) If the centre is soft, find P(chocolate is milk)

Answers:
a) 23/71
b) 39/71
c) 18/71
d) 27/71
e) 6/23
f) 10/39
 

tkhunny

Moderator
Staff member
Joined
Apr 12, 2005
Messages
9,708
Why do you doubt? Which one did you do incorrectly on purpose? They are fine. Now go with confidence to the next section.
 

susumandrai

New member
Joined
Feb 7, 2012
Messages
47
Why do you doubt? Which one did you do incorrectly on purpose? They are fine. Now go with confidence to the next section.
I was worried about these two:
e) If the chocolate is white, find P(hard centre)
My worry - If the chocolate is white means that my sample space is only the soft white and hard white, that is the reason why the answer is 6/23
f) If the centre is soft, find P(chocolate is milk)
My worry - If the centre is soft means my sample space is Dark, Milk, and White Chocolates of soft centre only. This is the reason why the answer is 10/39
 

tkhunny

Moderator
Staff member
Joined
Apr 12, 2005
Messages
9,708
Read the definition of "Conditional Probability" two or three more times and raise that confidence level!
 
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