Soybean meal is 18% protein, cornmeal is 9% protein, how many pounds of each should be mixed together to produce a mix that is 15% protein?

Question

If soybean meal is 18% protein and corn meal is 9% protein how muchsoybean meal should be mixed with 120 pounds of cornmean to produce a mix that is 15% protein?

Answer 1

Look at the protein concentrations.

120 pounds cornmeal at 9% has 0.09(120) pounds protein.

x pounds of soybean meal at 18% has 0.18x pounds protein

These are to sum to 120+x pounds of mix at 15% which has 0.15(120+x) pounds protein

 

0.09(120) + 0.18x = 0.15(120+x)

To clear decimals for ease of working multiply through by 100:

9(120) + 18x = 15(120+x)

1080 + 18x = 1800 + 15x

 

Finish solving for x to find the pounds of 18% protein soybean meal to add.