Homework Help: math

Posted by ibranian on Saturday, August 11, 2012 at 11:13pm.

You are asked to design a piping system that will connect a drilling rig 12 miles offshore to refinery on shore 20 miles down the coast. What values of x and y will give the least expensive connection if underwater pipe (x-section) costs $50.000 per mile and land-based pipe (y-section) costs $30.000 per mile?

math - Steve, Sunday, August 12, 2012 at 2:12pm
Draw a diagram. Let P be the point on shore where the pipe goes underwater.

Then if D is the drill rig, and R is the refinery,

x^2 = 12^2 + (20-y)^2
and the cost is
c = 50x+30y
c = 50√(144 + (20-y)^2) + 30y

dc/dy = 50(y-20)/√(y^2 - 40y + 544) + 30
dc/dy=0 when

y = 11
so, x = 15

Answer this Question

Related Questions

Calculus - An offshore well is 2 miles off the coast. The refinery is 4 miles ...
english - how to make this thesis on correct placement(Today the price of ...
science - from the point of view of an enviromentalist,what is probably the most...
Technology - I need help with these two questions: 1. Sheet metal and copper ...
Technology - (this post never got answered :() I need help with these two ...
math - A spray rig moving at 3 mph delivers 44 gallons per acre when the nozzles...
English II - I really need some help on a good thesis statement on offshore ...
social studies - From the point of view of an environmentalist, which is ...
social studies - From the point of view of an environmentalist, which is ...
social studies - From the point of view of an environmentalist, which is ...

For Further Reading

First Name:
School Subject:
Answer: