Hi R,
This question is used to illustrate how commercial dairy farms apply various scientific methods to monitor the growth of cows, sheeps etc. To entrepreneurs, time is money.
To handle this question, u must be familiar with the topics on differentiation, exponential, changes or small increment with respect to time. Sorry, long stories, not easy to explain here. More importantly, revise the chapter of Differentiation. In fact, the exponential equation looks frightening but the working is actually very simple, simpler than differentiate many other algebraic equations of x and y with powers or indices. Hope this helps. CY.