Sunday Times Teaser 2751 – Red Handed
by Andrew Skidmore
Published: 14 June 2015 (link)
I removed an even number of red cards from a standard pack and I then divided the remaining cards into two piles. I drew a card at random from the first pile and it was black (there was a whole-numbered percentage chance of this happening). I then placed that black card in the second pile, shuffled them, and chose a card at random from that pile. It was red (and the percentage chance of this happening was exactly the same as that earlier percentage).
How many red cards had I removed from the pack?