A variable of two populations has a mean of 55 and a standard deviation of 24 for one of the populations and a mean of 55 and a standard deviation of 40 for the other population. Complete parts (a) through (C). a. For independent samples of size 16 and 25, respectively, find the mean and standard deviation of x1 - x2. (Assume that the sampling is done with replacement or that the population is large enough.) The mean of x, - x2 is O. (Type an integer or a decimal. Do not round.) b. Must the variable under consideration be normally distributed on each of the two populations for you to answer part (a)? Explain your answer. c. Can you conclude that the variable x, - x2 is normally distributed? Explain your answer.
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
![### Problem Statement
A variable of two populations has a mean of 55 and a standard deviation of 24 for one of the populations and a mean of 55 and a standard deviation of 40 for the other population. Complete parts (a) through (c).
**a.** For independent samples of size 16 and 25, respectively, find the mean and standard deviation of \( \overline{x}_1 - \overline{x}_2 \). (Assume that the sampling is done with replacement or that the population is large enough.)
The mean of \( \overline{x}_1 - \overline{x}_2 \) is [ ].
(Type an integer or a decimal. Do not round.)
**b.** Must the variable under consideration be normally distributed on each of the two populations for you to answer part (a)? Explain your answer.
**c.** Can you conclude that the variable \( \overline{x}_1 - \overline{x}_2 \) is normally distributed? Explain your answer.
### Explanation
#### Part (a): Finding the Mean and Standard Deviation
To find the mean and standard deviation of \( \overline{x}_1 - \overline{x}_2 \), we're given:
- Mean and standard deviation for Population 1: μ1 = 55, σ1 = 24
- Mean and standard deviation for Population 2: μ2 = 55, σ2 = 40
- Sample sizes: n1 = 16, n2 = 25
To find the mean \( \mu \) of the difference in sample means \( \overline{x}_1 - \overline{x}_2 \):
\[ \mu_{\overline{x}_1 - \overline{x}_2} = \mu_1 - \mu_2 \]
To find the standard deviation \( \sigma \) of the difference in sample means \( \overline{x}_1 - \overline{x}_2 \):
\[ \sigma_{\overline{x}_1 - \overline{x}_2} = \sqrt{\left(\frac{\sigma_1^2}{n1}\right) + \left(\frac{\sigma_2^2}{n2}\right)} \]
#### Part (b): Normal Distribution in Each Population
Discuss whether the variable needs to be normally distributed in each of the two populations to determine whether the sample means \( \overline{x}_1 \](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F76b39ad3-98e6-4bd8-afd7-9890d91d962f%2F4a61a276-5b17-496b-a214-4e94475083d9%2F5d4gjjs_processed.png&w=3840&q=75)
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