An advertisement for a pineapple drink claims that the drink contains 15%pineapple juice. How much pure pineapple juice would have to be added to 8 quarts of the drink to obtain a mixture containing 50% pineapple juice?
Let's look at how much pineapple is in it now.
8 times .15= 1.2 quarts
So we take 1.2 from 8 to get 6.8 (non pineapple content)
Now take 6.8-1.2 to get 5.6
So if we add 5.6 pineapple to that 8 quarts let's look at the contents.
Non pineapple= 6.8 quarts
Pineapple= 1.2 + 5.6 = 6.8 quarts
then 6.8 + 6.8 = 13.6 quarts which is a perfect 50% mixture. so your answer is 5.6 quarts.