Medicine. The reaction times (in minutes) of a drug given to a random sample of 12 patients are
\begin{tabular}{llll}
3.3 & 3.3 & 5.6 & 5.6 \\
5.6 & 6.4 & 3.5 & 6.4 \\
5.8 & 5.9 & 6.6 & 6.6
\end{tabular}
a. Find the mean of the reaction times. $5.38 \mathrm{mins}$
(Type an integer or a decimal. Round to two decimal places.)
b. Find the standard deviation of the reaction times. $\square$ mins
(Type an integer or a decimal. Round to two decimal places.)

Step 1 ：Given the reaction times of a drug given to a random sample of 12 patients are 3.3, 3.3, 5.6, 5.6, 5.6, 6.4, 3.5, 6.4, 5.8, 5.9, 6.6, 6.6 minutes.

Step 2 ：To find the mean of the reaction times, we sum up all the values and divide by the number of values. The mean is \( \frac{3.3 + 3.3 + 5.6 + 5.6 + 5.6 + 6.4 + 3.5 + 6.4 + 5.8 + 5.9 + 6.6 + 6.6}{12} = 5.38 \) minutes.

Step 3 ：To find the standard deviation of the reaction times, we first find the variance. The variance is the average of the squared differences from the mean. After calculating the variance, we take the square root to find the standard deviation. The standard deviation is approximately 1.22 minutes.

Step 4 ：Final Answer: The mean of the reaction times is \( \boxed{5.38} \) minutes and the standard deviation of the reaction times is \( \boxed{1.22} \) minutes.