Question: A kayak rental company uses $C(t) = 12.5t + 30$ to find the total cost, in dollars, of renting a kayak for $t$ hours. The 30 is a one-time fee.
Jordan wrote: "$C(4) = 170$. Renting a kayak for 4 hours costs 170 in total."
Which statement about Jordan’s work is correct?
A
Jordan is correct.
B
Jordan added before multiplying. $C(4) = 80$, so renting a kayak for 4 hours costs 80 in total.
C
Jordan’s value is correct, but it means renting a kayak for 170 hours costs 4.
D
Jordan added before multiplying. $C(4) = 80$, so renting a kayak costs 80 per hour.
1. **State the problem:** We need to evaluate the cost of renting a kayak for 4 hours using the formula $$C(t) = 12.5t + 30$$ and check if Jordan's calculation $C(4) = 170$ is correct.
2. **Use the formula:** Substitute $t = 4$ into the formula:
$$C(4) = 12.5 \times 4 + 30$$
3. **Calculate multiplication first:**
$$12.5 \times 4 = 50$$
4. **Add the one-time fee:**
$$C(4) = 50 + 30 = 80$$
5. **Interpretation:** The total cost for 4 hours is $80$, not $170$.
6. **Check Jordan's work:** Jordan wrote $C(4) = 170$, which is incorrect because he likely added $12.5 + 30 = 42.5$ and then multiplied by 4, which is the wrong order of operations.
7. **Conclusion:** The correct statement is B: Jordan added before multiplying. $C(4) = 80$, so renting a kayak for 4 hours costs 80 in total.