Here are the shopping times (in minutes) for a sample of 6 shoppers at a particular dothing store. \( 30,37,28,20,27,26 \) Find the standard deviation of this sample of shopping times. Round your answer to two decimal places.
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To find the standard deviation of the shopping times, you first need to calculate the mean (average). The mean is given by: \[ \text{Mean} = \frac{\sum \text{shopping times}}{N} = \frac{30 + 37 + 28 + 20 + 27 + 26}{6} = \frac{168}{6} = 28 \] Next, calculate the variance by finding the squared differences from the mean: \[ \text{Variance} = \frac{\sum (x_i - \text{Mean})^2}{N - 1} = \frac{(30 - 28)^2 + (37 - 28)^2 + (28 - 28)^2 + (20 - 28)^2 + (27 - 28)^2 + (26 - 28)^2}{6 - 1} \] Calculating the squared differences: \[ (30 - 28)^2 = 4, \quad (37 - 28)^2 = 81, \quad (28 - 28)^2 = 0, \quad (20 - 28)^2 = 64, \quad (27 - 28)^2 = 1, \quad (26 - 28)^2 = 4 \] Now, sum the squared differences: \[ 4 + 81 + 0 + 64 + 1 + 4 = 154 \] So, the variance is: \[ \text{Variance} = \frac{154}{5} = 30.8 \] Finally, the standard deviation is the square root of the variance: \[ \text{Standard Deviation} = \sqrt{30.8} \approx 5.54 \] Thus, the standard deviation of the sample of shopping times is approximately \( 5.54 \) minutes (rounded to two decimal places).