Answer:
B.
Step-by-step explanation:
There are 20C4 = 4845 ways to take a sample of 4 from 20.
For choices A and C, the mean will be over-estimated if 3 of the 4 samples are of the higher value. There are (10C3)×10 = 1200 samples that will cause the mean to be over-estimated.
For choice D, every sample will correctly estimate the mean, so there are 0 samples that will cause the mean to be over-estimated.
For choice B, any sample that contains all 2s will over-estimate the mean. There are 19C4 = 3876 such samples.
Of the data sets listed, a sample of 4 from data set B is most likely to be one of the samples that will over-estimate the mean.
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nCk = n!/(k!(n-k)!)
