Question

Given that $$x\, \in \left[ {0,\,1} \right]$$   and $$y\, \in \left[ {0,\,1} \right].$$   Let $$A$$ be the event of $$\left( {x,\,y} \right)$$  satisfying $${y^2} \leqslant x$$   and $$B$$ be the event of $$\left( {x,\,y} \right)$$  satisfying $${x^2} \leqslant y.$$   Then :

A. $$P\left( {A \cap B} \right) = \frac{1}{3}$$  
B. $$A,\,B$$  are exhaustive
C. $$A,\,B$$  are mutually exclusive
D. $$A,\,B$$  are independent
Answer :   $$P\left( {A \cap B} \right) = \frac{1}{3}$$
Solution :
Probability mcq solution image
$$A =$$  the event of $$\left( {x,\,y} \right)$$  belonging to the area $$OTQPO$$
$$B =$$  the event of $$\left( {x,\,y} \right)$$  belonging to the area $$OSQRO$$
$$\eqalign{ & P\left( A \right) = \frac{{{\text{ar}}\left( {OTQPO} \right)}}{{{\text{ar}}\left( {OPQRO} \right)}} = \frac{{\int_0^1 {\sqrt x } \,dx}}{{1 \times 1}} = \left[ {\frac{2}{3}{x^{\frac{3}{2}}}} \right] = \frac{2}{3} \cr & P\left( B \right) = \frac{{{\text{ar}}\left( {OSQRO} \right)}}{{{\text{ar}}\left( {OPQRO} \right)}} = \frac{{\int_0^1 {\sqrt y } \,dy}}{{1 \times 1}} = \frac{2}{3} \cr & P\left( {A \cap B} \right) = \frac{{{\text{ar}}\left( {OTQS} \right)}}{{{\text{ar}}\left( {OPQRO} \right)}} = \frac{{\int_0^1 {\sqrt x } \,dx - \int_0^1 {{x^2}dx} }}{{1 \times 1}} = \frac{2}{3} - \frac{1}{3} = \frac{1}{3} \cr & P\left( A \right) + P\left( B \right) = \frac{2}{3} + \frac{2}{3} \ne 1. \cr & {\text{So, }}A{\text{ and }}B{\text{ are not exhaustive}}{\text{.}} \cr & P\left( A \right).P\left( B \right) = \frac{2}{3}.\frac{2}{3} = \frac{4}{9} \ne P\left( {A \cap B} \right). \cr & {\text{So, }}A{\text{ and }}B{\text{ are not independent}}{\text{.}} \cr & P\left( {A \cup B} \right) = 1,\,P\left( A \right) + P\left( B \right) = \frac{2}{3} + \frac{2}{3} \ne P\left( {A \cup B} \right). \cr & {\text{So, }}A{\text{ and }}B{\text{ are not mutually exclusive}}{\text{.}} \cr} $$

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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