SOLUTION: A pharmacist has 200 ml of an 80% iodine solution. How much distilled water must be added so that the new solution will be 46% iodine? (Round off to the nearest ml.) a) 67 ml b)

Question 718795: A pharmacist has 200 ml of an 80% iodine solution. How much distilled water must be added so that the new solution will be 46% iodine? (Round off to the nearest ml.)
a) 67 ml
b) 99 ml
c) 126 ml
d) 148 ml
How do I solve this problem?
Answer by jsmallt9(3758) (Show Source): You can put this solution on YOUR website!
If the there is 80% iodine in the 200ml, then there is 0.80 * 200 ml or 160ml of iodine in the solution. When we add distilled water to this 200 ml we will not be adding any more iodine. So the final solution will also have 160 ml of iodine.

If "x" is the amount of water we add, then 200 + x will be the total solution we have at the end. Since we want the solution to be 46% iodine, 160 ml will be 46 % of the total, (200 + x).

I don't know how you prefer to solve percent problems like this so I will provide to equations:

Translating "160 ml will be 46 % of the total, (200 + x)" into an algebraic expression we get:

(Note: Don't use percents in equations. Use the decimal or fractional equivalent. This is why it is 0.46 and not 46 in the equation.)
Using a proportion:

Pick an equation, solve it and then round the answer off to the nearest whole number. (If you want to check your work, solve both equations. You should get the same answer either way.)
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