The interviewer is interested in knowing how do you manage difficult situations, do you keep your head on your shoulders when difficulties arise or do you lose patience.

All the companies want to hire a person who is a problem solver and knows his way out of situations. Anyone who is willing to go that extra mile might be the choice of the hiring manager. An purchasing manager's job is to always come up with better solutions to the company's supply chain requirements and if you are someone who loves challenges then this just might be the job for you.

This can be answered with a difficult project encountered while in school or work. Difficult situations can be related to team dynamics, unrealistic expectations, incomplete directions, etc.

Describe the project, the difficulty and how/why it was difficult. Then describe how you dealt with it. Example might be taking a project team member aside and walking through the project elements, how they need to work on specific areas. If it was with a difficult teacher/boss, then describe how you communicated the issue(s) you were encountering, what you proposed to solve the issues, and ultimately the resolution.