TJ Prep Problems

TJ test prep practice problems  for our students and readers. The problems provide a very small sampling of what Optimal TJ Prep students work with.

TJ Prep - A Difficult Mixture Problem. Target Time 90 seconds.

Container A contains 20 L of 20%  antifreeze and 80% water. Container B contains 400 L of 90% antifreeze solution. How many L of container A should be replaced with an equal volume from container B so that the final solution in container A will have 45% antifreeze and 55% water?