Using proportions, it is found that the biologist should be expected to find 6 hairless chimpanzees in the troop.
A proportion is a fraction of a total amount.
In this problem, the mean of each sample is as follows: 3%, 5% and 4%.
Hence, from all samples, the mean should be expected to be of:
(3% + 5% + 4%)/3 = 4%.
Out of 150 chimpanzees:
0.04 x 150 = 6.
The biologist should be expected to find 6 hairless chimpanzees in the troop.
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