Answer: you added 6 liters of juice
Explanation:
You have 10 liters of a juice blend that is 60% juice. How many liters of pure juice need to be added in order to make a blend that is 75% juice?
Ten liters of a juice blend at 60% juice means you also have ten liters of a juice blend at 40% water. 10 x .40 yields 4 liters of water in your blend.
A juice blend of 75% has a water content of 25%. So the same 4 liters of water must represent 25% of the blend after adding more juice.
4/.25 = 16 liters. 16 x .75 = 12.
12 + 4 = 16.
That means after adding your juice you will have 16 liters of blend at 75% juice.
You originally had 10 liters at 60% and now you have 16 liters at 75% . Subtracting 10 from 16 means you added 6 liters of juice.