Question

A mother gives birth to an 8-pound baby. Every 3 months, the baby gains 4 pounds. If x is the age of the baby in months, then y is the weight of the baby in pounds. Find an equation of a line in the form y = mx + b that describes the baby's weight.

Y= _____________

Answer 1

y = (5 / 3)x + 8

Explanation:

At birth represents the beginning of time for the baby. Lets call this month zero. So here are your coordinates.

x = 0 y = 8 ----> at birth

x = 3 y = 13

x = 6 y = 18

x = 9 y = 23

Now we find the slope between each point. Since the common difference of y is 5 and the common difference in x is 3, the slope will be

slope = y / x = 5 / 3

Therefore, the equation of the line that represents this relationship is

Answer 2

y= 4/3x + 8

Explanation:

When the baby is born, it isn’t 0 pounds. We start with 8 pounds, which would be our y-intercept.

If you the baby grows 4 pounds every 3 months, we need to find how much it grows every month. 4/3 is as simple as it can get (unless you put it into decimal form)