Using proportions, it is found that he should be expected to count 48 Chinook at the dam.
A proportion is a fraction of a total amount.
Researching this problem on the internet, it is found that the proportion is that for each Chinook there are 2.5 steelheads. Hence, when there are 120 steelheads, the number of Chinooks is given by:
120/2.5 = 48.
Hence, he should be expected to count 48 Chinook at the dam.
More can be learned about proportions at https://brainly.com/question/24372153