# Probability-Combined-and-Conditional-probabilities -v2 by ClassOf1

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```									              Sub: Statistics                                                                         Topic: Probability

Question:

Simple, Combined and Conditional probabilities.

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1.    If two events A and B are mutually exclusive, what does the special rule of addition
state?
a) P (A or B) = P (A) + P (B)
b) P (A and B) = P (A) + P (B)
c) P (A and/or B) = P (A) + P (B)
d) P (A or B) = P (A) - P (B)
e) None of the above

Solution:

The addition rule states that, P (A or B) = P (A) + P (B) - P (A and B)
If two events A and B are mutually exclusive, then P (A and B) = 0
then P (A or B) = P (A) + P (B)

Correct answer is a) P (A or B) = P (A) + P (B).

2.    Which approach to probability is exemplified by the following formula?

Probability of an event happening = No. of times event occurred in the past

Total number of observations

a)   Classical approach
b)   Relative frequency appr
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