To calculate the estimated margin of error from the confidence interval $(48.8, 81.0)$, we can use the following formula:

$\text{Margin of Error} = \frac{\text{Upper Bound} - \text{Lower Bound}}{2}$

In this case:

$\text{Margin of Error} = \frac{81.0 - 48.8}{2} = \frac{32.2}{2} = 16.1$

So, the estimated margin of error is 16.1.

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For the sample mean, we can calculate it by finding the midpoint of the confidence interval:

$\text{Sample Mean} = \frac{\text{Upper Bound} + \text{Lower Bound}}{2}$

$\text{Sample Mean} = \frac{81.0 + 48.8}{2} = \frac{129.8}{2} = 64.9$

Thus, the sample mean is 64.9.

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Would you like further explanation or have any questions about this process?

Here are some related questions to delve deeper:

1. How does changing the confidence level affect the margin of error?
2. What assumptions are necessary for using a confidence interval in this context?
3. How would we interpret this confidence interval in terms of textbook prices?
4. How can we use this confidence interval to make business decisions in the store?
5. What role does sample size play in determining the width of a confidence interval?

Tip: The margin of error increases as the confidence level increases, reflecting more certainty in capturing the population mean within the interval.