A baby has its...

Question

A baby has its first doctor's visit when it is 2 months old and it weighs 9 pounds. The doctor tells the mother to expect the baby to gain 0.5 pounds each month.

Find an equation in the form y=mx+b that models the baby's weight , where x is the age of the baby's in months and y is it's weight in months.

Answer 1

We have a point (2, 9)

In 2 months from there the baby will weigh 10 pounds:  point (4, 10)

 

slope:  m = (10-9)/(4-2) = 1/2 or 0.5

y = 0.5x + b

 

Using (4, 10) as (x, y) find b

 

10 = 0.5(4) + b

10 = 2 + b

8 = b

 

Your equation is:  y = 0.5x + 8