Ok to be sure: relevant that the cards are 5?
To an extent Is 5 the minimum number in order to "force" a connection?
FA, as... Could the connection be made with 4 cards?
...the connection is made with only the four cards With 6?
Can we assume that the cards are shuffled
Yes and J does not know the order of the cards in the deck?
No! And that David picks all the 5 cards at random without D touching them in any way nor seeing the face down card in any way?
The four cards Yes, the other one No!In Step 3, Jack turns the 4 cards face up --> does it turn them all in once? Once at the ime?
Could be either Relevant?
NoDoes he shuffle the 5 cards all together (before turning the 4 up), put them all face up and guess what the 5th card was?
No does he do something relevant before predicting the 5th card?
By the context of your question, No E.g. he simply looks at the remaining 47 cards in the deck and deduce the 5th?
NoIs the first card taken before picked up at random as well?
No! Is this the card guessed/predicted right?
Yes! Is a connection made with the names of the cards?
And Yes Are various connections possible according to what are the 4 face up cards?
...and Yes.
I think I can call it here.
****SPOILER****
Jon is a magician performing a card trick. Jon shuffles the deck, sneaks a look at the top card, and asks David to pick a card. He forces the top card to David, then has David hand him four cards at random. He riffles the cards by his ear, saying the cards are telling him what David's chosen card is, then turns the four cards face up. Knowing what card David has, Jon improvises connections between the four cards, invariably leading to David's chosen card.
As an example (I'm using a random number generator for all of these cards), say David's card is the 5 of Diamonds, and the four cards Jon has are the 8 of Diamonds, 10 of Hearts, Queen of Diamonds, and 9 of Spades. Jon might say, "There is one black card, which can be set aside. There are two diamonds here, indicating your card is a diamond. But there are two diamonds, and the other red card is a 10. Therefore the cards are telling me to divide that number 10 by two. Is your card the 5 of Diamonds?"
Additionally, "David" was named for David Copperfield, and "Jon" for Jon Dorenbos, a former NFL long snapper who performed card tricks on America's Got Talent and finished third.
Nice job!