A random sample of size 225 is drawn from the population of mean μ and standard deviation σ. The sample mean follows the distribution with mean 100 and standard distribution 4/3. The value of μ and σ are:

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SSC CGL Tier-II ( JSO ) 2021 Official Paper ( Held On: 10 August 2022 )
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  1. (100, 18)
  2. (100, 15)
  3. (100, 24)
  4. (100, 20)

Answer (Detailed Solution Below)

Option 4 : (100, 20)
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Detailed Solution

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The correct answer is (100, 20).

Key Points 

  • The sample mean is an estimator of the population mean, but the true population mean is usually not known.
  • The standard deviation of the sample mean decreases as the sample size increases.
  • In general, larger sample sizes lead to more accurate estimates of population parameters.

​ Additional Information

  • The sample mean follows a normal distribution with mean 100 and standard deviation 4/3.
  • The sample size is 225.
  • The standard deviation of the population, σ, can be calculated using the formula σ = standard deviation of the sample mean * (square root of the sample size), where the standard deviation of the sample mean is 4/3.
  • σ = 4/3 * (square root of 225) = 20
  • So, the population mean is μ = 100 and the standard deviation is σ = 20.
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