I was given an excel sheet with some sales data on 3 product categories for an entire year.

The problem statement:
One of the product category (Say Product A) had a new pricing strategy implemented in last 6 months of the year (Price undercutting). Your task is to go through data and give your verdict on weather the comapny should continue with the new pricing strategy.

Process:
The interviewer (Generally senior product manager) is going to walk you through the case problem, show you data and take your initial clarifying questions. In my case she exited from the interview for 30 mins and let me work on my approach. Upon returning they expect you to walk them through your approach and have your verdict based on your analysis.

I was asked multiple question around my approach and I had to defend them with my rational though process.

I hope this helps.