So this part of the journey takes ...?... hours.
So this part takes ...?... hours.
Add the two times together, to find the total time . Then find the value of that makes a minimum.
(Answer: km from A)
The ends of the tank are squares. Let's suppose they measure meters by meters. And suppose that the tank is meters long. Then we have:2. An open rectangular tank (no top) with square ends is to have a volume of 6400 cubic meters. The base costs $75 per square meter and the sides $25 per square meter. What are the dimensions to build the tank at minimum cost?
Area of base = , at $75 per . So the cost of the base = $...?...
The total area of all four sides is at $25 per . So the cost of the sides = $...?...
So the total cost $C = ...?... (in terms of and )
Now the volume of the tank = area of base x height = .
But this is . So . So ...?... (in terms of ).
Now express in terms of only, and find the value of that will make a minimum.
(Answer: the tank measures 20 x 20 x 16 m.)
Can you complete these now?