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Home Questions HA4PCJDKQN
Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Probability

Question:

A random variable X has the following probability distributions

$X=x_i:$ 1 2 3 4
$P(X=x_i):$ 0.1 0.2 0.3 0.4

The mean and standard deviation of X are respectively.

Options:

2 and 3

3 and 1

3 and $\sqrt{2}$

2 and 1

Correct Answer:

3 and 1

Explanation:

The computation of mean and standard deviation is as follows:

$x_i$ $p_i=P(X=x_i)$ $p_ix_i$ $p_ix_i^2$

1

2

3

4

0.1

0.2

0.3

0.4

0.1

0.4

0.9

1.6

0.1

0.8

2.7

6.4
    $∑p_ix_i=3$ $∑p_ix_i^2=10$

$∴Mean = ∑p_ix_i=3$

Variance (X)= $∑p_ix_i^2-(∑p_ix_i)^2=10-9=1$

CUET Questions