the state test scores for 12 randomly selected high school seniors are shown on the right. complete parts…

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. 1427 1228 987 699 725 830 726 748 544 627 1441 950 (a) find the sample mean. \\( \\overline { x } = 911.0 \\) (round to one decimal place as needed.) (b) find the sample standard deviation. \\( s = \\square \\) (round to one decimal place as needed.)
Answer
Explanation:
Step1: Recall the formula for sample standard deviation
The formula for the sample standard deviation (s=\sqrt{\frac{\sum_{i = 1}^{n}(x_{i}-\bar{x})^{2}}{n - 1}}), where (n) is the sample size, (x_{i}) are the data points, and (\bar{x}) is the sample mean. Here (n = 12) and (\bar{x}=911.0).
Step2: Calculate ((x_{i}-\bar{x})^{2}) for each data point
For (x_1 = 1427): ((1427 - 911)^{2}=(516)^{2}=266256) For (x_2 = 1228): ((1228 - 911)^{2}=(317)^{2}=100489) For (x_3 = 987): ((987 - 911)^{2}=(76)^{2}=5776) For (x_4 = 699): ((699 - 911)^{2}=(- 212)^{2}=44944) For (x_5 = 725): ((725 - 911)^{2}=(-186)^{2}=34596) For (x_6 = 830): ((830 - 911)^{2}=(-81)^{2}=6561) For (x_7 = 726): ((726 - 911)^{2}=(-185)^{2}=34225) For (x_8 = 748): ((748 - 911)^{2}=(-163)^{2}=26569) For (x_9 = 544): ((544 - 911)^{2}=(-367)^{2}=134689) For (x_{10}=627): ((627 - 911)^{2}=(-284)^{2}=80656) For (x_{11}=1441): ((1441 - 911)^{2}=(530)^{2}=280900) For (x_{12}=950): ((950 - 911)^{2}=(39)^{2}=1521)
Step3: Sum up ((x_{i}-\bar{x})^{2})
(\sum_{i = 1}^{12}(x_{i}-\bar{x})^{2}=266256+100489 + 5776+44944+34596+6561+34225+26569+134689+80656+280900+1521) (\sum_{i = 1}^{12}(x_{i}-\bar{x})^{2}=1022181)
Step4: Calculate the sample standard deviation
(s=\sqrt{\frac{1022181}{12 - 1}}=\sqrt{\frac{1022181}{11}}\approx\sqrt{92925.545}\approx304.8)
Answer:
(s = 304.8)