A random variable X has expected value E(X) = 5 and E(X²) = 29. The variance is: MCQ with Answer and Explanation

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A random variable X has expected value E(X) = 5 and E(X²) = 29. The variance is:

A. 2

B. 5

C. 4

D. 24

Answer: Option C

Solution (By JKSSB Mock Tests)

Var(X) = E(X²) - [E(X)]² = 29 - 25 = 4.

This question belongs to: Accountancy and Statistics Statistics

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Practice More Statistics Questions

Question #1

Which of the following averages cannot be calculated if a dataset contains a zero?

A. Median

B. Harmonic mean

C. Arithmetic mean

D. Geometric mean

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Correct Answer: Option B

Explanation:
Harmonic mean involves reciprocals, so zero makes it undefined. Geometric mean with zero is zero, but it is defined; arithmetic and median unaffected.

This question belongs to: Accountancy and Statistics Statistics

Question #2

Crude Death Rate of 8 per 1000 means:

A. 8 deaths per 1000 live births

B. 8 deaths per 1000 population in a year

C. 8% of population died

D. 8 deaths per 1000 women

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Correct Answer: Option B

Explanation:
CDR = (Deaths/Mid-year population)×1000.

This question belongs to: Accountancy and Statistics Statistics

Question #3

The geometric mean of 1, 3, 9 is:

A. 3

B. 4.33

C. 3.3

D. 13

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Correct Answer: Option A

Explanation:
(1×3×9)^(1/3) = 27^(1/3) = 3.

This question belongs to: Accountancy and Statistics Statistics

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