Maria poured 1.5 liters of lemonade into each pitcher.
This question involves a problem-solving question which is involving the division of quantities into equal parts.
Maria had a total of 9 liters of lemonade. She divided the total amount by the number of pitchers, which is 6, to find out how much lemonade she should pour into each pitcher.
To do this, we can perform a simple division calculation:
9 liters ÷ 6 pitchers = 1.5 liters per pitcher
Therefore, Maria poured 1.5 liters of lemonade into each of the 6 pitchers, so that there was an equal amount of lemonade in each pitcher.