stats exam practice 1 no answers

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Apr 3, 2024

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1. The sample 10, 18, 20 has a standard deviation of 5.29 28 none of the other answers are correct 18.67 4.32 The deviation from mean needs to all add up to zero Remember to do n-1 which would be 3-1 so you get 56/2 S = Square root 56 /2 = 5.29

Standard deviation – how far the data values are from the mean on average. So the further the values are from the mean, the larger the standard deviation will be. Sample standard deviation - X – x bar represents the distance of each value fron the mean we square (x – x bar)^2 because some values may be negative when subtracting from the mean. Ex) score 20 and mean 30, deviation 20 – 30 = -10 We cant take square root of a negative number, so we square each deviation to make it positive. X = data X bar = sample mean Question 2 According to the empirical rule, a bell or mound shaped distribution will have approximately 95% of the data within what number of standard deviations of the mean? 2 none of the other answers are correct 1 4 3

According to the empirical rule (also known as the 68-95-99.7 rule), for a bell-shaped or mound- shaped distribution: • Approximately 68% of the data falls within one standard deviation of the mean. • Approximately 95% of the data falls within two standard deviations of the mean. • Approximately 99.7% of the data falls within three standard deviations of the mean. So, approximately 95% of the data will be within 2 standard deviations of the mean. 3. A manufacturer claims to have built a home stereo speaker that is 4 feet tall but uses an average of only 30 watts of power. A sample of 40 speakers from the manufacturer found that they used an average of 32 watts of power. The appropriate hypotheses to test the manufacturer’s claim are? A. Ho: M=30 versus HA:M=not equal30 B. Ho: M=32 versus HA: M=not equal32 C. Ho: M=30 versus HA:M=32 D. Ho: M=30 versus HA:M>30 E. None of the above Further testing

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