Thread: Applications of Systems,

Problem 1
-Soybean meal is 16% protein; corn meal is 9% protein. How many pounds of each should be mixed together to get a 350 pound mixture that is 12% protein?


And someone please check if I did this problem correctly....
The difference between two numbers is 11. Twice the smaller number plus three times the larger is 123. What are the numbers?
I got 90 and 101 is that correct?

Originally Posted by dvnswl

Problem 1
-Soybean meal is 16% protein; corn meal is 9% protein. How many pounds of each should be mixed together to get a 350 pound mixture that is 12% protein?

Let be the mass of soybean in the mix and
be the mass of corn meal in the mix.

Then as these add to pounds:

.

The mass of protien in the mix is:

,

which is 12% of the total mass, so:

,

which may be rearranged to:

.

So now you have a pair of simultaneous linear
equations in x and y to solve.

RonL

Originally Posted by dvnswl

And someone please check if I did this problem correctly....
The difference between two numbers is 11. Twice the smaller number plus three times the larger is 123. What are the numbers?
I got 90 and 101 is that correct?

Since twice 90 is greater than 123, your answer cannot be right.

Let the numbers be and with , then:

,

and:



Now twice the first equation plus the second gives:

,

or:

,

so:

,

and then:

.

RonL