Question: You are running a business selling homemade bread. Your weekly revenue from the sale of $q$ loaves of bread is
$R(q) = 63q - 0.2q^2$ dollars, and the weekly cost of making $q$ loaves of bread is $C(q) = 20 + 17q$ dollars.
a. Find the weekly profit function $P(q)$.
$P(q) =$
b. Find the production level $q$ that maximizes the weekly profit.
$q = $ loaves of bread
c. Find the maximum profit.
1. **State the problem:**
We have revenue function $$R(q) = 63q - 0.2q^2$$ and cost function $$C(q) = 20 + 17q$$ for $q$ loaves of bread.
We want to find:
a. The profit function $P(q)$.
b. The production level $q$ that maximizes profit.
c. The maximum profit.
2. **Find the profit function $P(q)$:**
Profit is revenue minus cost:
$$P(q) = R(q) - C(q)$$
Substitute the given functions:
$$P(q) = (63q - 0.2q^2) - (20 + 17q)$$
Simplify:
$$P(q) = 63q - 0.2q^2 - 20 - 17q$$
$$P(q) = (63q - 17q) - 0.2q^2 - 20$$
$$P(q) = 46q - 0.2q^2 - 20$$
3. **Find the production level $q$ that maximizes profit:**
Since $P(q)$ is a quadratic function with a negative coefficient for $q^2$, it opens downward and has a maximum at its vertex.
The vertex of $$P(q) = -0.2q^2 + 46q - 20$$ is at
$$q = -\frac{b}{2a}$$ where $a = -0.2$ and $b = 46$.
Calculate:
$$q = -\frac{46}{2 \times (-0.2)} = -\frac{46}{-0.4} = 115$$
So, the profit is maximized when producing $$q = 115$$ loaves.
4. **Find the maximum profit:**
Substitute $q=115$ into $P(q)$:
$$P(115) = 46(115) - 0.2(115)^2 - 20$$
Calculate each term:
$$46 \times 115 = 5290$$
$$115^2 = 13225$$
$$0.2 \times 13225 = 2645$$
So,
$$P(115) = 5290 - 2645 - 20 = 2625$$
**Final answers:**
- a. $$P(q) = 46q - 0.2q^2 - 20$$
- b. $$q = 115$$ loaves
- c. Maximum profit $$P(115) = 2625$$