Question 1087076
I hope there is a typo and the problem should read that after 6 months the baby weighs 17 pounds and is 25 inches tall, because 66 months is 5 and a half years old, and a five year old child of that size would be dead or about to die from malnutrition or starvation.
 
If a child is born weighing 11 pounds and measuring 22 inches in length,
and 6 months later weighs 17 pounds and measures 25 inches in length,
assuming that weight, {{{W(t)}}} , and length, {{{H(t)}}} ,
are linear functions of time {{{t}}} , in months,
those functions are
{{{W(t)=((17-11)/6)t+11}}} <---> {{{highlight(W(t)=t+11)}}} and
{{{H(t)=((25-22)/6)t+22}}} <---> {{{highlight(H(t)=(1/2)t+22)}}} .
Then, assuming that the child continues to grow linearly,
at 1 year old {{{t=12}}}, the child's weight and height would be
{{{W(12)=12+11}}} <---> {{{highlight(W(12)=23)}}} and
{{{H(12)=(1/2)12+22)}}} <---> {{{highlight(H(12)=28)}}} .