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Home Questions SYPACHF46M
Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Probability

Question:

If the probability distribution table for no, of "Heads'' in three throws of coin is 

X

0

1

2

3

P(X=x)

1/8

3/8

3/8

1/8

Then Var (X) is:

Options:

3/4

3/8

3/16

3/32

Correct Answer:

3/4

Explanation:

xi  

Pi    

Pixi

Pixi2

0

1/8

0

0

1

3/8

3/8

3/8

2

3/8

6/8

12/8

3

1/8

3/8

9/8

 

 

$∑Pixi=\frac{12}{8}=\frac{3}{2}$

$∑Pixi^2=\frac{24}{8}=3$

 

$Var(X)=∑P_ix_i^2-(∑P_ix_i)^2 = 3-(\frac {3}{2})^2=\frac{3}{1}-\frac {9}{4}=\frac {12-9}{4}=\frac{3}{4}$

CUET Questions