1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Matrix word problem- Precalculas

  1. May 2, 2012 #1
    1. The problem statement, all variables and given/known data
    Factory A and B sent rice to store 1 and 2. Factory A sent 10 loads and factory B sent 24. Store 1 used 17 loads and store 2 used 17 loads. It cost 200$ per load to ship from factory A to store 1. It cost 350$ per load to ship from factory A to store 2. It cost 300$ per load to ship from factory B to store 1. It cost 250$ per load from factory B to store 2. A tiotal of 8350$ was spent on shipping. How many loads were shipped from each factory to each store.

    2. Relevant equations

    3. The attempt at a solution
    The problem that I am having is setting up the equations to create a matrice that can accurately reflect the problem.
    some scribbles were
  2. jcsd
  3. May 2, 2012 #2


    Staff: Mentor

    Start by defining what your variables mean.
    What do x, y z, E, and e represent?

    After you do that, see if you can translate the statements in English in the problem to mathematical equations.
  4. May 2, 2012 #3
    So I now have
    Defining the variables gives me.
    A1= loads from factory A to store 1
    B1= Loads from factory B to store 1
    A2= Loads from factory A to store 2
    B2= Loads from factory B to store 2
    The answer came out with 27, 17, -10, and 0. So it's clear I set it up incorrectly.
  5. May 2, 2012 #4


    Staff: Mentor

    Now that you have identified some variables, let's start translating the problem statement.

    This can be translated into two equations.

    One of them is
    A1 + A2 = 10

    Do you understand what this is saying?
    If so, what other equation can we get from the sentence above?
  6. May 2, 2012 #5
    B1 + B2 = 24
    A1 + A2 = 10
    yes, what it is saying is that Loads from factory B to store1 + Loads from factory B to store2 = 24 loads. Same concept with A1 + A2 = 10
  7. May 2, 2012 #6

    Ray Vickson

    User Avatar
    Science Advisor
    Homework Helper

    If A1, A2, B1, B2 are the factory-store shipments (in obvious labelling), we have
    [tex] \begin{array}{l}A1+A2 = 10\\
    B1 + B2 = 24\\
    A1+B1 = 17\\
    A2 + B2 = 17
    Here, you have 4 unknowns and 4 equations, but if you try to solve them you will find that you can't get a complete solution. Basically, one of the 4 equations follows from the other three, so you really have only 3 independent equations.

    You need a 4th, independent, equation, and that is where the cost information comes in. So, omit one of the equations above and replace it by the cost equation---then solve.

  8. May 3, 2012 #7
    thanks that got it done.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook