The average weight of a male child's brain is 970 grams at age 1 and 1270 grams at age 3.† (a) Assuming that the relationship between brain weight y grams and age t years is linear, write a linear model for the data.

(b) What is the slope?
m =

What does it tell you about brain weight?
At birth, a human brain weighs 970 grams.

A human male's brain weight is constant for his entire lifespan.

The weight of a male human brain is decreasing by m grams/year.

A human male's brain reaches a maximum weight at age 3.

The weight of a male human brain is increasing by m grams/year.

(c) Use your model to estimate the average brain weight at age 2.
g

(d) Use your school's library, the Internet, or some other reference source to find the actual average brain weight at age 2. How close was your estimate?