# Word problem.. anyone?

• Apr 16th 2008, 10:18 PM
lilikoipssn
Word problem.. anyone?
Liquid A has 10 grams of element X per liter. Liquid B has 15 milligrams of element Y per cm^3 (there are 1000 milligrams in a gram and 1000 cm^3 in a liter). It is desired to make 130 grams of molecule Z. To make 18 grams of Z requires 2 grams of X and 16 grams of Y. How many liters of each liquid should be used?
• Apr 17th 2008, 01:34 AM
Sean12345
I will quickly try to tackle this. (Evilgrin)

We have;

$\displaystyle (1)~~~A~=~10gl^{-1}~of~X$

$\displaystyle (2)~~~B~=~15mgcm^{-3}~of~Y$

$\displaystyle ~=~15\cdot10^{-3}gcm^{-3}$

$\displaystyle ~=~15gl^{-1}$

$\displaystyle 18g~of~Z~=~2g~of~X~+~16g~of~Y$

$\displaystyle \implies~130g~of~Z~=~\frac{130}{9}g~of~X~+~\frac{1 040}{9}g~of~Y$

We want $\displaystyle \frac{130}{9}g~of~X$ hence we need $\displaystyle \frac{130}{90}l$ of $\displaystyle A$
We also want $\displaystyle \frac{1040}{9}g~of~Y$ hence need $\displaystyle \frac{208}{27}l$ of $\displaystyle B$