Logical thinking 4 Probability and odds

Roulette is a popular randomized game at most casinos

In this lesson, let's discuss odds and probability, and how certain things effect odds, while others don't.

Warm Up: 

A man was playing roulette. Red had come up six times in a row. He knew that it was very improbable for red to come up seven times in a row, therefore black was almost certain to come up next. He'd been having a bad night and it was too late to turn back now, so he took an educated guess, and put the rest of his gambling money on black.

Is this a good bet? Why?


To discuss odds and probability, we can use phrases like: "Odds are it will..." or "Chances are it will..."

Can you think of any more words or phrases?

Discuss the probability of the following:

  • How's the weather going to be next week?
  • If you follow a sports team, what are the chances of them winning the next match?
  • What are the odds of the yen increasing in value next year?

On a different but related topic, let's discuss the fallacy of sunk costs. A common idiom for this is "Throwing good money after bad." Can you think of any examples?


Using the information provided, as well as any facts or data that you know of, discuss the odds of the following situations.

  1. Sales of this product are very low, but we already spent money making and marketing this product, so we have to sell it again next year.
  2. The price of housing in Tokyo has been rising. So considering the fact that housing prices in cities around the world have been increasing, it's safe to say the odds of Tokyo prices increasing are very good. I think I'll buy an investment property in Tokyo.
  3. Economists say that a recession happens every seven years. Do you think this will happen in the future? Will it be on schedule?