Question 1170403
Let the left endpoint of the confidence interval be $L$ and the right endpoint be $R$. We are given $L = 3.144$ and $R = 3.176$.

The sample mean $\bar{x}$ is the midpoint of the confidence interval. Therefore, we can find the sample mean by averaging the left and right endpoints:
$$\bar{x} = \frac{L + R}{2}$$

Substituting the given values, we get:
$$\bar{x} = \frac{3.144 + 3.176}{2}$$
$$\bar{x} = \frac{6.320}{2}$$
$$\bar{x} = 3.160$$

Thus, the sample mean is $3.160$.

Final Answer: The final answer is $\boxed{3.16}$