Answer:
Speed of the truck should be 64.03 miles per hour to minimize the cost.
Explanation:
Data provided in the question:
Distance = 150 miles
Wage = $14 per hour
Cost of fuel = ( v² ÷ 250 )
Now,
Total time taken = Distance ÷ speed
= 150 ÷ v
Therefore,
Total cost, TC = Wage + Cost of fuel
= $14 × (150 ÷ v) + ( v² ÷ 250 )
= [tex]\frac{2100}{v}+\frac{v^2}{250}[/tex]
for point of minima differentiating with respect to 'v'
TC'(v) = [tex]-\frac{2100}{v^2}+\frac{2v}{250}[/tex] = 0
or
[tex]-\frac{2100}{v^2}+\frac{2v}{250}[/tex] = 0
or
[tex]\frac{v}{125}=\frac{2100}{v^2}[/tex]
or
v³ = 2100 × 125
or
v = ∛262500
or
v = 64.03 miles per hour
hence,
Speed of the truck should be 64.03 miles per hour to minimize the cost.