Twenty pounds of a salt-water solution contains fifteen percent salt. How much water must be added to weaken the solution to twelve percent salt? 3 lb 5 lb 12 lb
answer will be 5 lb
Lets see how this is worked out. 20 pounds of water which is 15 % salt. that would mean there is (.15)(20) or 3 pounds of salt. Now we want to add water so that this 3 pounds of water is 12 % of the mixture: 3=.12x x=3/.12=25 pound mixture. We have 20 already so we only need to add 25-20 or 5 pounds.
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