<prompt> A newborn is double his height at birth by what age?2 12 years3 12 years4 12 years5 12 years  <response>: Ans. is c i.e., 4 12 years Height The average birth height is 50 cm. The height gain in first year is around 25 cm 50 of birth height. The height of a child becomes double the birth height at around 4li years and becomes triple by 12 years of age. After the age of 4 years, a child grows at rate of 6 cmyear.AgeHeightBirth50 cm3 months60 cm9 months70 cm1 year75 cm2 years90 cm4 12 years100 cm 