How do I solve this problem on potassium chromate?

Question

A concentrated solution of potassium chromate is added to a solution that is 0.1M Ba 2+ and 0.1M Sr 2+. Which ion will precipitate first? What is the percentage of ion remaining when the other ion begins to precipitate?

Answer 1

We need to know the Ksp for barium chromate and for strontium chromate. Cannot solve this without that info.