When making a 1L 1X PBS solution from the stock 10X concentration, how would you do it; which formula would you use?
Your interviewer will ask situation- and knowledge-based questions to understand how you outline your process and how well you can explain concepts to others. In this case, buffers and reagents come at concentrations that may or may not be suitable for direct use. This is a standard calculation used routinely as a Research Associate. Remember, you do not need to ask what PBS is as it's irrelevant to the result, and it's a common reagent in most laboratories.
"100mL of 10X PBS and 900mL water is needed to make a 1X 1L solution. I would use the formula C1V1 C2V2 where C1 equals the initial concentration of the solution, V1 equals the initial volume of the solution, C2 represents the final concentration of the solution, and V2 is the final volume of the solution."