The state test scores for 12 randomly selected high school seniors are shown on the right. Complete parts (a) through (c) below.
Assume the population is normally distributed.
$\begin{array}{lll}1421 & 1230 & 981 \\ 697 & 726 & 839 \\ 721 & 744 & 541 \\ 627 & 1447 & 946\end{array}$
(a) Find the sample mean.
$\bar{x}=910.0$ (Round to one decimal place as needed.)
(b) Find the sample standard desviation.
$s=$
(Round to one decimal place as needed.)

Step 1 ：Given the state test scores for 12 randomly selected high school seniors are: 1421, 1230, 981, 697, 726, 839, 721, 744, 541, 627, 1447, 946.

Step 2 ：To find the sample mean, we need to sum up all the scores and divide by the number of scores. The sample mean is given as \(\bar{x}=910.0\).

Step 3 ：To find the sample standard deviation, we need to subtract each score from the mean, square the result, sum up these squared results, divide by the number of scores minus 1 (this is called the variance), and finally take the square root of the variance.

Step 4 ：Subtracting each score from the mean and squaring the result gives us the variance, which is 92910.90909090909.

Step 5 ：Taking the square root of the variance gives us the sample standard deviation, which is 304.81290834036065.

Step 6 ：Rounding to one decimal place, the sample standard deviation is \(\boxed{304.8}\).