1. The problem statement, all variables and given/known data Suppose that during the first year after its hatching, the weight of a duck increases at a rate proportional to its weight. The duck weighed 2 pounds when hatched, and 3.5 lbs at age 4 months. How many lbs will it weight at 6 months? A) 4.2 lbs B) 4.6 lbs C) 4.8 lbs D) 5.6 lbs E) 6.5 lbs Answer: (B) 4.6 lbs 2. Relevant equations 3. The attempt at a solution I assumed this was a linear equation and used the points (0, 2) and (4, 3.5) to find the slope, .375, and the equation of the line to be y=.375x+2. Then i plugged in 6 and got y(6)=.375(6)+2 = 4.25. But the answer is 4.6. Is the graph not a linear equation? Maybe since it says "weight increases at a rate proportional to its weight", it is an exponential function?? Then, how would I find f(6)??