It appears you've uploaded an image containing a mathematical expression. The expression seems to be related to statistical or sample mean calculations, involving the formula:

$\bar{x} \pm 0.99 \left( \frac{\sigma}{\sqrt{n}} \right)$

This looks like an expression for a confidence interval (perhaps 99% confidence) for a population mean $\mu$, where:

• $\bar{x}$ is the sample mean,
• $\sigma$ is the population standard deviation,
• $n$ is the sample size.

The term $\frac{\sigma}{\sqrt{n}}$ represents the standard error of the mean, and multiplying it by 0.99 is likely the margin of error for a 99% confidence level.

Would you like more details or an explanation of the steps involved in calculating a confidence interval? Let me know if you have further questions or if you'd like to solve a specific example.

Here are some related questions you might find interesting:

1. How do you calculate the margin of error for a confidence interval?
2. What does it mean to have a 99% confidence interval?
3. How does the sample size $n$ affect the confidence interval width?
4. How would you calculate a confidence interval if the population standard deviation is unknown?
5. Can this formula be used for other levels of confidence (e.g., 95%)?

Tip: In practice, using larger sample sizes reduces the margin of error and gives more precise estimates of the population parameter.