Whitney was curious if sample mean was an unbiased estimator of population mean. She placed ping pong balls numbered from 0 to 32 in a drum and mixed them well. Note that the mean of the population is 16.
She then took a random sample of 5 balls and calculated the mean of the sample. She replaced the balls and
repeated this process for a total of 50 trials. Her results are summarized in the dotplot below, where each dot
represents the sample mean from a sample of 5 balls.
5
10
15
20
25
Sample mean
Based on these results, does sample mean appear to be a biased or unbiased estimator of population mean?
Hint: The population mean is 16.