Upper Limit of a t-Interval for Concrete Strength

A materials lab crushes a random sample of 6 concrete cubes from a single batch and records compressive strength, in MPa:

$12, \quad 15, \quad 9, \quad 14, \quad 10, \quad 12$

The population standard deviation $\sigma$ is unknown, so the lab estimates it from the sample (using the $n-1$ divisor) and builds a $95\%$ confidence interval for the batch mean strength $\mu$:

$\text{CI} = \bar{x} \pm t^{*} \cdot \frac{s}{\sqrt{n}}$

For $95\%$ confidence with $6$ observations, use $t^{*} = 2.571$.

What is the upper limit of this confidence interval?

Round your answer to 2 decimal places.