A couple has two children. At least one of them is a boy. Assuming the probability of having a boy or girl is 50%, what is the probability that both children are boys?
If you answered 1/2, you’re not without comrades, but the generally accepted answer by statisticians (though not without debate) is 1/3. This is because there are four possible combinations: boy-boy, boy-girl, girl-boy and girl-girl. Since we are told one of the children is a boy (but we don’t know if it’s the first or second child), we can rule out the girl-girl combination, leaving three remaining options. Only one out of 3 is boy-boy, so we get a 1/3 chance.
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.
Cut #1 – Down the center of the cake (vertically) leaving two equal halves.
Cut #2 – Across the center of the cake (horizontally) leaving four equal slices.
Cut #3 – Through the middle edge of the cake slicing all four of the pieces in equal halves, leaving eight equal slices (four equal tops and four equal bottoms).
A lemon. It’s a citrus fruit whose juice is acidic and can be used to conduct electricity for motors. A car or other purchase that has problems is known as a lemon and can be expensive to repair. Lemons have a tart flavor but do little harm (unless you get it in a cut, then it hurts like the dickens). The old saying goes, “When life gives you lemons, make lemonade” (I know, it’s spelled aid not ade but it sounds the same and wouldn’t make any sense the other way. It all works out nicely when the riddle is told instead of read.)