find the average

Question

In testing an experimental diet for beef cows, it was determined that the (average) live weight w (in kilograms) of a cow was statistically a linear function of the number of days d after the diet was started, where 0 ≤ d ≤ 300. The weight of a cow starting the diet was 125 kg and 100 days later it was 245 kg. Determine w as a linear function of d and find the average weight of a cow when d = 200.

Answer 1

Even more interestingly, it has been recently reported that adding very small amounts of seaweed to the "fattening" diets of beef cattle, enormously reduces their emission of methane gas, while also increasing their conversion of feed nutrients into mass. That's a win-win situation, since methane emission from cows is a significant proportion of greenhouse gases generation worldwide (they emit the reducing gas as H2, without greenhouse effect). It might make you wonder if seaweed addition could also abate methane generation from anaerobic processes elsewhere, such as from marshes. That could be a topic for a really neat research project (i.e., cellulosic waste digestion in flasks, with complete gas collections -- you bubble the exit gases up through acidified salt solutions, so that the CO2, CH4, and H2 are quantitively collected -- , with global implications! Just sayin'! --Cheers, -- Mr. d.

P.S. some seaweeds contain sulfated sugars, so pure seaweed digesters emit substantial H2S -- be forewarned!

Answer 2

Use tw0-point form from Algebra 1:

(y - 125) / (x - 0) = (245 - 125) / (100 - 0)