Solution Found!
Travel cost The cost of a trip that is L miles long,
Chapter 10, Problem 40E(choose chapter or problem)
Travel cost The cost of a trip that is L miles long, driving a car that gets m miles per gallon, with gas costs of $p/gal is C = Lp/m dollars. Suppose you plan a trip of L = 1500 mi in a car that gets m = 32 mi/gal, with gas costs of p = $3.80/gal.
a. Explain how the cost function is derived.
b. Compute the partial derivatives \(C_{L}, C_{m}, \text { and } C_{p}\). Explain the meaning of the signs of the derivatives in the context of this problem.
c. Estimate the change in the total cost of the trip if L changes from L = 1500 to L = 1520, m changes from m = 32 to 31, and p changes from $3.80 to p = $3.85.
d. Is the total cost of the trip (with L = 1500 mi, m = 32 mi/gal, and p = $3.80) more sensitive to a 1% change in L, m, or p (assuming the other two variables are fixed)? Explain.
Questions & Answers
QUESTION:
Travel cost The cost of a trip that is L miles long, driving a car that gets m miles per gallon, with gas costs of $p/gal is C = Lp/m dollars. Suppose you plan a trip of L = 1500 mi in a car that gets m = 32 mi/gal, with gas costs of p = $3.80/gal.
a. Explain how the cost function is derived.
b. Compute the partial derivatives \(C_{L}, C_{m}, \text { and } C_{p}\). Explain the meaning of the signs of the derivatives in the context of this problem.
c. Estimate the change in the total cost of the trip if L changes from L = 1500 to L = 1520, m changes from m = 32 to 31, and p changes from $3.80 to p = $3.85.
d. Is the total cost of the trip (with L = 1500 mi, m = 32 mi/gal, and p = $3.80) more sensitive to a 1% change in L, m, or p (assuming the other two variables are fixed)? Explain.
ANSWER:Solution 40E
Step 1
Consider the following problem
To derive the cost function
The total distance of trip is miles
And consumption of gas is mile per gallon
And cost of gas is
Since consumption of gas in mile distance is gallon
Therefore consumption of gas in 1 mile distance is
Since cost of 1 gallon gas is
Therefore cost of gallon gas is
Now cost of 1 mile distance is
Since total distance is miles
Therefore cost of distance is
Suppose total cost of trip is denoted by then