What is the fraction of 400 ml of 1 liter?

To find the fraction of 400 ml in 1 liter, we need to express both quantities in the same unit. Since 1 liter is equal to 1000 ml, the fraction can be calculated as 400 ml out of 1000 ml, which simplifies to 2/5 or 0.4. So, the fraction of 400 ml in 1 liter is 2/5 or 0.4.