Brain Workout (M, 119): Elimination


  • Your mission is to determine how many children that it took more than five minutes to find, by doing some elimination.
  • Try solving the problem first with the brain only – no use of pen and paper, or other aid.
  • Good luck!


Twenty children were playing hide and seek in the park yesterday, with their teacher who counted to thirty before setting out to find them.

Of the total number of children, two fifths were boys and the rest girls. Three-quarters of the boys wore yellow jumpers, as did half of the girls. Of those remaining, half of the boys and half of the girls wore green jumpers, and every other child wore a blue jumper.

Half of the number of children in blue jumpers were found in under five minutes, as were half of the boys in yellow jumpers and two girls in green jumpers. Their teacher took longer than five minutes to find the rest of the children.

How many children took more than five minutes to be found by the teacher?

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