A sample size of 25 is drawn from a normal population with a mean of 62. If the standard deviation from the sampling distribution is 3.5, what is the standard deviation of the orig... A sample size of 25 is drawn from a normal population with a mean of 62. If the standard deviation from the sampling distribution is 3.5, what is the standard deviation of the original population?
Understand the Problem
The question asks for the standard deviation of the original population based on the provided information about a sample size and the standard deviation of the sampling distribution. This involves applying statistical concepts to find the population standard deviation.
Answer
The standard deviation of the original population is \( \sigma = 17.5 \).
Answer for screen readers
The standard deviation of the original population is ( \sigma = 17.5 ).
Steps to Solve
- Identify the given information
We know the following:
- Sample size ($n$) = 25
- Standard deviation of the sampling distribution ($\sigma_{\bar{x}}$) = 3.5
- Use the formula for the standard deviation of the sampling distribution
The relationship between the standard deviation of the sampling distribution and the standard deviation of the original population is given by the formula:
$$ \sigma_{\bar{x}} = \frac{\sigma}{\sqrt{n}} $$
Where:
- $\sigma_{\bar{x}}$ is the standard deviation of the sampling distribution
- $\sigma$ is the standard deviation of the original population
- $n$ is the sample size
- Rearrange the formula to solve for the population standard deviation
To find the population standard deviation ($\sigma$), we rearrange the formula:
$$ \sigma = \sigma_{\bar{x}} \cdot \sqrt{n} $$
- Plug in the values and calculate
Substituting the known values into the equation:
$$ \sigma = 3.5 \cdot \sqrt{25} $$
Calculating $\sqrt{25}$:
$$ \sqrt{25} = 5 $$
Thus,
$$ \sigma = 3.5 \cdot 5 $$
- Perform the final calculation
Calculating ( \sigma ):
$$ \sigma = 17.5 $$
The standard deviation of the original population is ( \sigma = 17.5 ).
More Information
This problem illustrates a key concept in statistics regarding the relationship between the sampling distribution and the population, specifically how the standard deviation of a sample differs from that of the entire population. A larger sample size typically results in a smaller standard deviation for the sampling distribution.
Tips
- Confusing the standard deviation of the sample with the standard deviation of the population.
- Not correctly applying the formula or miscalculating the square root.
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