Given Bernard weighs 7.5 pounds at birth.The question is asking us to assume that Bernard development proceeds normally.We need to find Bernard birth after a year.
It is observed that birth of a child triples or is thrice (3 times ) the weight at birth.As Bernard is weighing 7.5 pounds so he will triple or be 3times of this weight.
Bernard weight after a year= 3x7.5=22.5 pounds.