The memo solves this word problem using a tree diagram, but my inclination went more towards two-way contingency tables - potato, potato. More than the tool we ended up using, the bigger task with this question was translating a problem from words to maths (and boy were there wooooorrrrddddssss 😂). I had to puzzle quite a bit for this one and in hindsight, I’m thinking maybe this would have been a useful place to try to use trial and error first in order to figure out a game plan for the question. Like I have often said, the goal of trial and error isn’t necessarily to stumble on the answer by mistake, but rather to inspect how it is that you verify your guess. That often gives you a clue about the equation that you are implicitly trying to solve. In this case, I could have started by guessing that maybe there are 70 meat sandwiches, which would mean that there are 50 cheese sandwiches. Do these numbers match up with the probability that the question provided? Anyway. Fun question that turns out not to be very difficult computationally, but just tricky to find a starting point.
Highlights:
Turning a word problem into an equation
Tree diagrams / 2-way contingency tables