Algebra word problem

Question

A urine sample has a total volume of 1,900 mL, and it has a total of 800 mg protein. Find the amount of protein in 380 mL of this same urine sample.

Answer 1

Set up a ratio or proportion as...

 

mL:mg :: 1900:800 :: 380:x

 

We can rewrite ratios as fractions and cross-multiply...

 

1900        380

-------   =   -----

 800           x

 

1900x=800(380).....cross-multiply

1900x=304,000......simplify

    ∴ x=160.............divide both sides by 1900

 

Let's check...

1900/800=380/160...substitute for "x"

         2.38=2.38..........true, √check, our solution

                                     is correct

 

Always check your solution and work!

 

So 160mg protein is present in the 380 mL urine sample.