A software developer wants to know how many new computer games people buy each year. A sample of 1064 people was taken to study their purchasing habits. Construct the 99% confidence interval for the mean number of computer games purchased each year if the sample mean was found to be 9.6. Assume that the population standard deviation is 1.8. Round your answers to one decimal place.

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### Confidence Interval Calculation Example

#### Problem Statement:
A software developer wants to know how many new computer games people buy each year. A sample of 1064 people was taken to study their purchasing habits. Construct the 99% confidence interval for the mean number of computer games purchased each year if the sample mean was found to be 9.6. Assume that the population standard deviation is 1.8. Round your answers to one decimal place.

#### Solution:

To calculate the 99% confidence interval for the mean, use the following formula:

\[ CI = \bar{x} \pm Z \left(\frac{\sigma}{\sqrt{n}}\right) \]

Where:
- \(\bar{x}\) = Sample mean = 9.6
- \(Z\) = Z-value for 99% confidence (approx. 2.576)
- \(\sigma\) = Population standard deviation = 1.8
- \(n\) = Sample size = 1064

**Steps:**
1. Calculate the standard error (SE) of the mean:
   \[ SE = \frac{\sigma}{\sqrt{n}} = \frac{1.8}{\sqrt{1064}} \]

2. Multiply the standard error by the Z-value to find the margin of error (MOE):
   \[ MOE = Z \times SE \]

3. Calculate the confidence interval:
   - Lower endpoint: \(\bar{x} - MOE\)
   - Upper endpoint: \(\bar{x} + MOE\)

Insert the calculated values into the answer boxes.

#### Answer Section:
- **Lower endpoint:** [Input calculated value]
- **Upper endpoint:** [Input calculated value]

**Useful Tools:**
- Tables
- Keypad

### Note:
Use the "Tutor" feature if you need assistance with understanding the concepts or calculations. Always ensure answers are rounded to one decimal place as specified.
Transcribed Image Text:### Confidence Interval Calculation Example #### Problem Statement: A software developer wants to know how many new computer games people buy each year. A sample of 1064 people was taken to study their purchasing habits. Construct the 99% confidence interval for the mean number of computer games purchased each year if the sample mean was found to be 9.6. Assume that the population standard deviation is 1.8. Round your answers to one decimal place. #### Solution: To calculate the 99% confidence interval for the mean, use the following formula: \[ CI = \bar{x} \pm Z \left(\frac{\sigma}{\sqrt{n}}\right) \] Where: - \(\bar{x}\) = Sample mean = 9.6 - \(Z\) = Z-value for 99% confidence (approx. 2.576) - \(\sigma\) = Population standard deviation = 1.8 - \(n\) = Sample size = 1064 **Steps:** 1. Calculate the standard error (SE) of the mean: \[ SE = \frac{\sigma}{\sqrt{n}} = \frac{1.8}{\sqrt{1064}} \] 2. Multiply the standard error by the Z-value to find the margin of error (MOE): \[ MOE = Z \times SE \] 3. Calculate the confidence interval: - Lower endpoint: \(\bar{x} - MOE\) - Upper endpoint: \(\bar{x} + MOE\) Insert the calculated values into the answer boxes. #### Answer Section: - **Lower endpoint:** [Input calculated value] - **Upper endpoint:** [Input calculated value] **Useful Tools:** - Tables - Keypad ### Note: Use the "Tutor" feature if you need assistance with understanding the concepts or calculations. Always ensure answers are rounded to one decimal place as specified.
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