What you've described here sounds like a written case similar to what BCG has. I've uploaded some samples here: (ask me for a password)
The best way to prepare is the following:
- Train mental math. I posted the main tips here: https://www.preplounge.com/en/consulting-forum/tips-to-do-big-multiplications-in-my-mind-726#a1422
- Prepare for a regular case interview - it helps a lot. Basically, prep lounge website is about it
- Practice making slides. Look for publically available MBB presentations for reference. Good books are "Pyramid Principle" and "How to make it with charts"
- Practice reading cases fast and prioritizing the information. I found useful two sources:
- Written cases you'll be able to find in google or in case books. I've seen a couple in "Vault Guide to the Case Interview" and "Insead Business Admission Test"
- Harvard cases - either buy or try to find online. You can find a couple of MIT cases here for free: https://mitsloan.mit.edu/LearningEdge/Pages/Case-Studies.aspx Unfortunately free cases don't have the prep questions.
The appropriate structure for BCG written case (that you may also apply for your presentation) is:
Slide 1: Context, Objective, Recommendations
Slide 2-4: Analysis (Usually 1 slide with a table, 1 slide with graphs and 1 slide with pros and cons)
Slide 5: Next steps or risks & mitigation