OLIVIA 4, DAISY 1
Jessica had two sisters, Olivia and Daisy. Not wanting to favour one over the other, she wanted to visit the two sisters equally often. To avoid making difficult decisions, she would just turn up at random at the station and wait for whicever train came first. Olivia lived up the line and Daisy lived down the line, and she knew that the ‘up’ trains and the ‘down’ trains both turned up at ten minute intervals.
Unfortunately, Jessica’s plan was a failure – she found she was visiting Olivia four times as often as Daisy. What had gone wrong with her cunning plan?