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If X be a random variable taking values `x_(1),x_(2),x_(3),….,x_(n)` with probabilities `P_(1),P_(2),P_(3)`,…..`P_(n)`, respectively. Then, Var (x) is equal to …….. .

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Var (X) = `E(X)^(2)-[E(X)]^(2)`
=`underset(i=1)overset(n)SigmaX^(2)P(X)-"["underset(i=1)overset(n)SigmaXP(X)"]"^(2)`
`=SigmaP_(i)x_(i)^(2)-(SigmaP_(i)x i)^(2)`
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NCERT EXEMPLAR-PROBABILITY-Probability
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  2. For the following probability distribution. E(X^(2)) is equal to

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  3. Suppose a random variable X follows the binomial distribution with par...

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  4. In a college, 30% students fail in physics, 25% fail in Mathematics an...

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  5. A and B are two students. Their chances of solving a problem correctly...

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  6. If a box has 100 pens of which 10 are defective, then what is the prob...

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  7. If P(A)gt0 and P(B)gt0. Then A and B can be both mutually exclusive an...

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  8. If A and B are independent events, then A' and B' are also independen...

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  9. If A and B are mutually exclusive events, then they will be independen...

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  10. Two independent events are always mutually exclusive.

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  11. If A and B are two independent events, then P( A and B)=P(A)cdotP(B)

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  12. Another name for the mean of a probability distribution is expected va...

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  13. If A and B' are independent events, then P(A'cupB)=1-P(A)P(B').

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  14. If A and B are two events suc that P(A)gt0 and P(A)+P(B)gt1, then P(B/...

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  15. If A,B and C are three independent events such that P(A)=P(B)=P(C )=...

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  16. If A and B are two events such that P(A/B)=p,P(A)=p,P(B)=1/3 and P(Acu...

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  17. If A and B are such that P(A'cupB')=2/3andP(AcupB)=5/9 then P(A')+P(B'...

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  18. If X follows Binomial distribution with parameters n=5, p and P(X=2)=9...

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  19. If X be a random variable taking values x(1),x(2),x(3),….,x(n) with pr...

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  20. Let A and B be two events. If P(A/B)=P(A), then A is …. of B

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