If you have a few minutes, please try these brain teasers.
First please consider Linda, a 31-year-old woman, single and bright. When she was a student, in high school and in college too, she was deeply involved in social justice issues, and also participated in environmental protests.
Which is more probable about Linda’s occupation today?
a) Linda works as a TV reporter;
b) Linda is a bank teller;
c) Linda is a bank teller, and she’s very active in the environmental movement.
Quick, what’s your answer?
a) or b) or c)?And, in what precise order?.
Here’s the solution:
First, ignore how you ranked a), as it is irrelevant to this mind game.
The key is this: If you ranked c) as more probable than b), you are wrong…and in very good company.
That’s what most people tend to answer the first time they face this particular brain teaser, and it reflects a very pervasive cognitive bias, technically called a “conjunction fallacy.”
Statistically speaking, it is more probable that Linda is a bank teller, which is a whole category, that she is both a bank teller AND also active in the environmental movement, which is a subset of the whole category of all bank tellers.
Here you are a few more fun and quick brain teasers to exercise your mind.
Try to GUESS the answers to the questions below based on your own approach.
The goal is not to find out (or Google) the right answer, but to identify the logical approach that will help “guesstimate” an appropriate range, say + or – 30% of the actual answer, and then to complete the calculations (ideally mentally, but you can also take notes) to provide an estimate.
Ready. Set. Go!
Brain teaser questions:
1) How many times heavier than a mouse is an elephant?.
2) How many firefighters are there in San Francisco?.
3) How many trees are there in NYC’s Central Park?
Again, the key here is to exercise your brain and cognitive skills, to plan the steps towards the solution, and then to do the mental calculations to find a reasonable range. The goal is not to find the precise correct answer.
Here are the solutions.
1) Around 150,000. An average elephant weighs 4,000 kg on average; an average mouse 25 grams.
2) Around 350 firefighters on duty on any given day, out of a pool of 1700 firefighting overall staff.
3) There are over 26,000 trees (of approximately 175 species) in the Park.
How close did you come?