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Did You Work It Out? The Solution to Our Riddle from the E-News Issue of July 2014

Who predicts the right sequence?

Probability calculation, riddle, brain teaser, e-news, solution, eggs
Which sequence of colored eggs will probably be observed first?

In a laying battery, half the chickens lay brown eggs and the other half lay white eggs. These are transported individually and in random order to the packing station on a conveyor belt.

Sarah and Tim work sorting the eggs at the packing station. In order to make their work a little more entertaining, they try to predict certain sequences. The person whose prediction is confirmed first, wins. Sarah predicts white, brown, brown; Tim says brown, brown, white.

Who has the greater chance of winning and how great is it?


Tim only wins if two brown eggs are delivered first. Sooner or later, a white egg will follow, e.g. bbw, bbbw, bbbbw, etc. Tim wins in the case of any of these sequences. The probability for two brown eggs to be delivered first is 1/2 * 1/2 = 1/4.

In all other cases, Sarah wins, as the sequence bb is always preceded by a white egg. Sarah therefore has a greater chance (75 %) of winning the bet.