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Question

The variance of degenerate random variable is:

This question was previously asked in
SSC CGL 2018 (Tier 2) Statistics Previous Year Paper (22-feb-2018)
The correct answer is

0

A degenerate random variable \(X\) takes a single value \(c\) with probability 1, so \(E[X]=c\) and

\[\text{Var}(X) = E[(X-c)^2] = E[0] = 0\]

There is no dispersion because the variable never deviates from its mean. Hence the variance is 0.

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Similar Questions

  1. The fourth central moment of a mesokurtic distribution is 243. Its standard deviation is:

  2. The standard deviation of the first 10 natural numbers is 3.028. What will be the standard deviation of the first 20 natural numbers?

  3. If n 1= 10 and n 2= 5 are the sizes, \(\rm\bar{x}_1\)  = 7 and  \(\rm\bar{x}_2\)  = 4 are the means and σ 1= 1 and σ 2= 1 are the standard deviations of two series of data. If combined mean  \(\rm\bar{x}\)  = 6, then the variance of the combined series with size n 1+ n 2is equal to:

  4. If the sum of 10 observations is 12 and the sum of their squares is 18, then the standard deviation is:

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Important Questions from Variance and Standard Deviation

  1. Mean of 100 observations is 50 and standard deviation is 10. If 5 is added to each observation, then what will be the new mean and new standard deviation respectively?

  2. When sampling is done without replacement then standard error of mean is:

  3. Consider a population that is finite, and sampling is with replacement. If the variance of the population is 2176.8 with a sample size of 16, then the variance of the sampling distribution of means is:

  4. If \(\rm \displaystyle \sum_{i = 1}^{10}x_i = 110\)  and  \(\rm \displaystyle \sum_{i = 1}^{10}x_i^2 = 1540\)   then what is the variance?

  5. The sum of deviations of n numbers from 10 and 20 are p and q respectively. If (p - q)2 = 10000, then what is the value of n?

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