ERJ Brainteaser - April
30 Mar 2026
Each month, ERJ sets a weekly brainteaser, with questions of varying degrees of difficulty. Readers supplying the most accurate (and stylish) answers are then considered for the prestigious Brainiac of the Month title
Question 1: Green and black
Moulded rubber seals are produced in pairs - one green, the other black - and transferred to containers holding more than 250 but less than 350 of the mouldings in total.
However, one seal has been lost from a container so that, if two seals were randomly drawn out, the probability of them being the same colour would be exactly 50%.
If there are more green seals than black seals, can you work out mathematically the colour of the missing seal?
Email your answer: correct replies on Friday.
