The article asks about the minimal number of persons required for achieving a probability 1/2 that (a.) At least two share a birthday, (b.) At least one shares the reader's birthday. A basic question about the necessary number of checks underlies both problems.

As the number of independent tosses of a fair coin grows, the rates of heads and tails tend to equality. This is misinterpreted by many students as being true also for the absolute numbers of the two outcomes, which, conversely, depart unboundedly from each other in the process. Eradicating that misconception, as by coin-tossing experiments,…

The article presents an attempt to analyse Monty's dilemma by means of conversational formula-free dialogues and to simulate the problem by composing isomorphic stories. The crucial roles of specifying the underlying scenarios and explicating epistemic and probabilistic assumptions are highlighted.

Two contestants debate the notorious probability problem of the sex of the second child. The conclusions boil down to explication of the underlying scenarios and assumptions. Basic principles of probability theory are highlighted.

When two sealed envelopes contain money, one twice as much as the other, a player should be indifferent between them. But when one envelope is opened, one's decision should vary as a function of the observed value and one's subjective probabilities.

The older one gets, the more one's life expectancy exceeds the population's given expectancy (at birth). Yet longevity is finite. This apparent paradox is analysed probabilistically with reference to empirical demographic data.

An elusive probability paradox is analysed. The fallacy is traced back to improper use of a symbol that denotes at the same time a random variable and two different values that it may assume.

Uniformity, that is, equiprobability of all available options is central as a theoretical presupposition and as a computational tool in probability theory. It is justified only when applied to an appropriate sample space. In five studies, we posed diversified problems that called for "unequal" probabilities or weights to be assigned to the given…

One interpretation of the Pearson product-moment correlation ("r"), correlation as the probability of originating from common descent, important to the genetic measurement of inbreeding, is examined. The conditions under which "r" can be interpreted as the probability of "identity by descent" are specified, and the…

Six- to 14-year olds added "winning" beads to an urn of "losing" beads in order to generate equal probabilities of choosing a winning bead from each of two urns. Found that 13-year olds integrated the two dimensions (winning and losing beads), the youngest children relied on one dimension, and 9- to 10-year olds partly combined…

Discusses students' preconceptions of randomness and offers an alternative way to think about the concept using the idea of complexity. That is, the randomness of a sequence can be measured by the difficulty of encoding it. Methods of judging complexity and implications for teaching are discussed. (Contains 30 references.) (MKR)

This study, conducted with children 4 to 11 years old, indicates that probability concepts could be introduced early in the elementary grades. (MK)