Since the father is walking 3 times as fast as his son, their speeds are in a ratio of 3:1 respectively
They started at the same time so they will cover distance at the same ratio of 3:1
Each portion of the distance they covered is 16/(3+1) = <<16/(3+1)=4>>4m
The father covered three portions of the distance which is 3*4m = <<3*4=12>>12m from his end
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