Chapter 11.4, Problem 84E

To determine

To calculate: The percentage $y$(of total personal consumption) as the function of time $t$ by using direct substitution and the rate at which the percentage an individual spends on food is changing on $\text{November}1$ using chain rule if it is given that the percentage $y$(of total personal consumption) an individual spends on food is given by the function $y=33x^{-0.63}$ percentage points $\left(2.5\le x\le 4.5\right)$, where $x$ represents the percentage the individual spends on recreation and a college student finds expenditure percent of personal consumption on recreation given by the function $x=3.5+0.1t$ where $t$ is the time in months since $\text{January1}$.