Math Trek Math When intuition and math probably look wrong A twist on the Two Children Problem shows how information can steer what looks probable By Julie Rehmeyer June 28, 2010 at 12:07 pm Share this:EmailFacebookTwitterPinterestPocketRedditPrint I have two children, one of whom is a son born on a Tuesday. What is the probability that I have two boys? WORKING IT OUT This grid gives a visual way of calculating the answer to the question, “Among families that have two children, one of whom is a boy born on a Tuesday, how many have two boys?” It shows all the possible variations of birth day and gender for children in a two-child family. The families with the saturated colors are those which might qualify, while those that are shaded out are eliminated. The row gives the birth day of the older child and the column gives the birth day of the younger, while the color represents the sex of each child. If the older child is a boy born on Tuesday, then the family must lie on the Tuesday row and the box representing the older child must be blue. If the younger child is a boy born on Tuesday, the family must lie on the Tuesday column and the box representing the younger child must be blue. The combination of all those boxes show all the possible families that qualify. The total number of saturated boxes is 27. The number of saturated boxes in which both children are boys is 13. So the probability is 13/27. Bill Casselman More Stories from Science News on Math Math This intricate maze connects the dots on quasicrystal surfaces By Skyler WareJuly 29, 2024 Math Scientists find a naturally occurring molecule that forms a fractal By Emily ConoverApril 12, 2024 Math How two outsiders tackled the mystery of arithmetic progressions By Evelyn LambFebruary 26, 2024 Physics A predicted quasicrystal is based on the ‘einstein’ tile known as the hat By Emily ConoverJanuary 25, 2024 Physics Here’s how much fruit you can take from a display before it collapses By Darren IncorvaiaJanuary 4, 2024 Math Here are some astounding scientific firsts of 2023 By Cassie MartinDecember 18, 2023 Math ‘Is Math Real?’ asks simple questions to explore math’s deepest truths By Evelyn LambOctober 16, 2023 Math An enduring Möbius strip mystery has finally been solved By Emily ConoverOctober 10, 2023