please use the calculator method      The scores on the Wechsler Intelligence Scale for Children (WISC) are normally distributed with a standard deviation of sigma - 10. A SRS of 25 children from Southwest Virginia is taken to determine the mean mew of all children from Southwest Virginia. If the mean of this sample is 104.32, find a 95% confidence interval for. What is the margin of error for this interval?

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The scores on the Wechsler Intelligence Scale for Children (WISC) are

normally distributed with a standard deviation of sigma - 10. A SRS of 25 children from Southwest Virginia is taken to determine the mean mew of all children from Southwest Virginia. If the mean of this sample is 104.32, find a 95% confidence interval for. What is the margin of error for this interval?

### Some Common Values of Z*

This table provides values of Z* corresponding to different confidence levels, commonly used in statistical analysis for constructing confidence intervals. The Z* values are crucial for determining the margin of error in statistical estimates.

| **Confidence Level** | **Tail Level** | **Z*** |
|---------------------|---------------|--------|
| 60%                 | 0.20          | 0.84   |
| 80%                 | 0.10          | 1.28   |
| 90%                 | 0.05          | 1.645  |
| 95%                 | 0.025         | 1.96   |
| 96%                 | 0.02          | 2.05   |
| 98%                 | 0.01          | 2.33   |
| 99%                 | 0.005         | 2.576  |

### Explanation

- **Confidence Level**: This indicates the percentage of all possible samples that can be expected to include the true population parameter. For example, a 95% confidence level means that we can be 95% certain that the true parameter is within our interval estimate.

- **Tail Level**: The probability in each tail of the normal distribution that is not included in the confidence interval. It is calculated as (1 - Confidence Level)/2. For a 95% confidence level, the tail level is 0.025.

- **Z* Value**: The Z-score, representing the number of standard deviations a data point is from the mean. It acts as a multiplier for the standard error in interval calculations. For instance, a Z* of 1.96 at 95% confidence level means the data point is 1.96 standard deviations away from the mean in a normal distribution.

These values help in determining how wide the confidence interval around a sample statistic should be, thereby giving an indication of the precision of the estimate.
Transcribed Image Text:### Some Common Values of Z* This table provides values of Z* corresponding to different confidence levels, commonly used in statistical analysis for constructing confidence intervals. The Z* values are crucial for determining the margin of error in statistical estimates. | **Confidence Level** | **Tail Level** | **Z*** | |---------------------|---------------|--------| | 60% | 0.20 | 0.84 | | 80% | 0.10 | 1.28 | | 90% | 0.05 | 1.645 | | 95% | 0.025 | 1.96 | | 96% | 0.02 | 2.05 | | 98% | 0.01 | 2.33 | | 99% | 0.005 | 2.576 | ### Explanation - **Confidence Level**: This indicates the percentage of all possible samples that can be expected to include the true population parameter. For example, a 95% confidence level means that we can be 95% certain that the true parameter is within our interval estimate. - **Tail Level**: The probability in each tail of the normal distribution that is not included in the confidence interval. It is calculated as (1 - Confidence Level)/2. For a 95% confidence level, the tail level is 0.025. - **Z* Value**: The Z-score, representing the number of standard deviations a data point is from the mean. It acts as a multiplier for the standard error in interval calculations. For instance, a Z* of 1.96 at 95% confidence level means the data point is 1.96 standard deviations away from the mean in a normal distribution. These values help in determining how wide the confidence interval around a sample statistic should be, thereby giving an indication of the precision of the estimate.
Expert Solution
Step 1

Confidence Interval

l1  = X - tα  S. E. of X  - Lower limitl2  = X  +  tα  S. E. of X  - Upper limit

given in the question σ = 10,  n=25 , X  = 104. 32

tα at 5% level of significance = 1.96

S.E. of  X

 = σn  =1025  = 2

Confidence interval

l1  = 104.32 - 1.962     = 100.4l2   = 104.32 + 1.962      = 108.24

Hence the confidence interval would be-

(100.4< P < 108.24)

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