Skewed left, because the sample sizes are less than 30 and the sampling variability is unknown.
Alex’s times for running a mile are Normally distributed with a mean time of 5.28 minutes and a standard deviation of 0.38 seconds.
Chris’s times for running a mile are Normally distributed with a mean time of 5.45 seconds and a standard deviation of 0.2 seconds.
Ten of Alex’s times and 15 of Chris’s times are randomly selected. Let x Overbar Subscript Upper A Baseline minus x Overbar Subscript Upper C represent the difference in the mean times for Alex and Chris.
What is the standard deviation?
The standard deviation is a statistic that measures the dispersion of a dataset relative to its mean and is calculated as the square root of the variance.
Normal, because both population distributions are Normal.
Uniform, because both sample sizes are less than 30.
Skewed right, because the difference in times cannot be negative.
Skewed left, because the sample sizes are less than 30 and the sampling variability is unknown.
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