Question

Let $${E^c}$$ denote the complement of an event $$E$$. Let $$E,\,F,\,G$$   be pairwise independent events with $$P\left( G \right) > 0$$   and $$P\left( {E \cap F \cap G} \right) = 0.$$     Then $$P\left( {{E^c} \cap {F^c}|G} \right)$$    equals :

A. $$P\left( {{E^c}} \right) + P\left( {{F^c}} \right)$$
B. $$P\left( {{E^c}} \right) - P\left( {{F^c}} \right)$$
C. $$P\left( {{E^c}} \right) - P\left( F \right)$$  
D. $$P\left( E \right) - P\left( {{F^c}} \right)$$
Answer :   $$P\left( {{E^c}} \right) - P\left( F \right)$$
Solution :
We have
Probability mcq solution image
$$\eqalign{ & \because \,E \cap F \cap G = \phi \cr & P\left( {{E^c} \cap {F^c}/G} \right) = \frac{{P\left( {{E^c} \cap {F^c} \cap G} \right)}}{{P\left( G \right)}} \cr & = \frac{{P\left( G \right) - P\left( {E \cap G} \right) - P\left( {G \cap F} \right)}}{{P\left( G \right)}} \cr & \left[ {{\text{From ven diagram }}{E^c} \cap {F^c} \cap G = G - E \cap G - F \cap G} \right] \cr & = \frac{{P\left( G \right) - P\left( E \right)P\left( G \right) - P\left( G \right)P\left( F \right)}}{{P\left( G \right)}} \cr & = 1 - P\left( E \right) - P\left( F \right) \cr & = P\left( {{E^c}} \right) - P\left( F \right) \cr & \left[ {\because \,E,\,F,\,G{\text{ are pairwise independent}}} \right] \cr} $$

Releted MCQ Question on
Statistics and Probability >> Probability

Releted Question 1

Two fair dice are tossed. Let $$x$$ be the event that the first die shows an even number and $$y$$ be the event that the second die shows an odd number. The two events $$x$$ and $$y$$ are:

A. Mutually exclusive
B. Independent and mutually exclusive
C. Dependent
D. None of these
Releted Question 2

Two events $$A$$ and $$B$$ have probabilities 0.25 and 0.50 respectively. The probability that both $$A$$ and $$B$$ occur simultaneously is 0.14. Then the probability that neither $$A$$ nor $$B$$ occurs is

A. 0.39
B. 0.25
C. 0.11
D. none of these
Releted Question 3

The probability that an event $$A$$ happens in one trial of an experiment is 0.4. Three independent trials of the experiment are performed. The probability that the event $$A$$ happens at least once is

A. 0.936
B. 0.784
C. 0.904
D. none of these
Releted Question 4

If $$A$$ and $$B$$ are two events such that $$P(A) > 0,$$   and $$P\left( B \right) \ne 1,$$   then $$P\left( {\frac{{\overline A }}{{\overline B }}} \right)$$  is equal to
(Here $$\overline A$$ and $$\overline B$$ are complements of $$A$$ and $$B$$ respectively).

A. $$1 - P\left( {\frac{A}{B}} \right)$$
B. $$1 - P\left( {\frac{{\overline A }}{B}} \right)$$
C. $$\frac{{1 - P\left( {A \cup B} \right)}}{{P\left( {\overline B } \right)}}$$
D. $$\frac{{P\left( {\overline A } \right)}}{{P\left( {\overline B } \right)}}$$

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Probability


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