Answer:
(a)20.65 lbs.
(b)1.88 lbs/month.
Step-by-step explanation:
The median weight of the boy can be approximated by the function:
[tex]w(t)=7.42+1.92t-0.0074t^2+0.000446t^3[/tex]
Where t is measured in months; and
w is measured in pounds.
(a)When the baby is 7 months
Approximate Weight,
[tex]w(7)=7.42+1.92(7)-0.0074(7)^2+0.000446(7)^3\\=20.65$ pounds (to two decimal places)[/tex]
The approximate weight of the baby at age 7 months is 20.65 lbs.
(b) If [tex]w(t)=7.42+1.92t-0.0074t^2+0.000446t^3[/tex]
Rate of change, [tex]w'(t)=1.92-0.0148t+0.001338t^2[/tex]
At t=7 months
[tex]w'(7)=1.92-0.0148(7)+0.001338(7)^2\\w'(7)=1.88$ lbs/month[/tex]
The rate of change for the baby's weight with respect to time at age 7 months is approximately 1.88 lbs/month.