Linda is 31 years old, single, outspoken, and very bright. She majored in philosophy. As a student, she was deeply concerned with issues of discrimination and social justice, and also participated in anti-nuclear demonstrations.
Which is more probable?
1) Linda is a bank teller.
2) Linda is a bank teller and is active in the feminist movement.
Most people guess number two, but the probability of two events occurring together is always less than or equal to the probability of either one occurring alone. This problem is known as the Conjunction Fallacy.
Amir has three children. One is the same age as the first number in his age, another is the same age as the second number in his age, and the third is the same age as the sum of the two numbers in his age. None of the children are the same age and the total of everyone’s ages is 45. How old is Amir?
Fred was almost done packing for the day, with five packages left. Unfortunately, Fred dropped the labels and had no idea which label went to which package. What is the probability that Fred managed to correctly label exactly four of the five packages?
Zero. If Fred had correctly labeled four packages, the fifth label would belong to the fifth package and all packages would be correctly labeled. Therefore it is impossible to mislabel exactly four packages.