1. ## Word Problem

A substance is 99% water. Some water evaporates, leaving a substance that is 98% water. How much of the water has evaporated?

I am having a very difficult time setting up an algebraic equation to solve this problem. I honestly do not know where to begin. None of the work I have done on this problem is worth posting. Perhaps I am over-thinking this one...

2. ## Re: Word Problem

How much water left?
How much water did you have left?

Answer these questions and you nearly are done.

3. ## Re: Word Problem

Hi themathkid.
Try this 100grams of a salt solution contains 1 gm 0f salt
let x = water evaporated gms
100-x = weight 0f remaining solution .What is the new conc of salt in terms of f(x)?

4. ## Re: Word Problem

Originally Posted by bjhopper
Hi themathkid.
Try this 100grams of a salt solution contains 1 gm 0f salt
let x = water evaporated gms
100-x = weight 0f remaining solution .What is the new conc of salt in terms of f(x)?
f(x) = 1/(100-x)

or

f(x) = 1/(99-x)

Does this mean that 50% of the water has evaporated?!?!?

5. ## Re: Word Problem

Hi the mathkid,
After the x gms of water evaporate the salt weight does not change ( it is not volative)The desired salt concentration is 2% or .02 fraction so the equation is 1/100-x = .02
x= 50 grams or 50% of the orginal solution