I don't think this problem needed conditional probabilities. I had a go at coming up with a combinatorics approach and a simulation approach to verify the first

I don't think this problem needed conditional probabilities. I had a go at coming up with a combinatorics approach and a simulation approach to verify the first attempt. It's here if you're interested: https://medium.com/@benjamin22-314/get-all-four-toys-b8653c2c46c5 https://medium.com/@benjamin22-314/get-all-four-toys-b8653c2...