Increase in height in first year is by

Length at bih- 50 cms, while at the end of 1st year, it is 75 cms, i.e., height increases by 25cms, which will be 50% 50% of 50cms (at bih) will be 25cms, and by adding this 25cms to 50cms it'll account to 75 cms( at the end of 1yr) Ref: Nelson's 20th edition, pg 84-89