A truck is to be driven 300 miles on a freeway at a constant speed of x miles per hour. Speed laws require that 35 ≤ x ≤ 55. Assume that fuel costs $1.35 per gallon and is consumed at the rate of 2 + 1 600 %01 x 2 galloons per hour. Given that the driver's wages are $13 per hour, at what speed should the truck be driven to minimize the truck owner's expenses?

Question

Business

Salvatore Reeves

27 April, 09:23

A truck is to be driven 300 miles on a freeway at a constant speed of x miles per hour. Speed laws require that 35 ≤ x ≤ 55. Assume that fuel costs $1.35 per gallon and is consumed at the rate of 2 + 1 600 %01 x 2 galloons per hour. Given that the driver's wages are $13 per hour, at what speed should the truck be driven to minimize the truck owner's expenses?

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Answers (1)

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Stephen Goodwin · Answer 1

x = 55 Miles per hour

Explanation:

Length of trip, L = 300 miles

If "x" is the velocity in miles per hour, time t taken to complete the trip = Length / velocity

t = L / x

There are two components of cost:

The cost per hour for fuel is C dollars, and the driver is paid W dollars per hour.

Hence the cost for the entire trip = The cost per hour for fuel x total number of hours + Hourly cost driver x total number of hours = C*t + W*t

C = 2 + (1/600) * x², W = 13.00 and t = 300 / x

Hence our total cost of the trip,

TC (x) = (2 + (1/600) * x²) * (300 / x) + 13 * (300 / x)

TC (x) = (4500 / x) + (x / 2)

In order to minimise this total cost, we need to differentiate this with respect to x and equate it to zero:

TC' (x) = ((4500 / x) + (x / 2)) ' = 0

( - 4500 / x²) + (1 / 2) = 0

this equation gives x₁ = - 94.868 and x₂ = 94.868

as we know that 35 ≤ x ≤ 55

we can say that x = 55 Miles per hour (which is the maximum value)