Two jokers are added to a $52$ card deck and the entire stack of $54$ cards is shuffled randomly. What is the expected number of cards that will be strictly between the two jokers?

  52/3.

Step-by-step explanation:

There are (54·53)/2 = 1431 ways the 2 jokers can be placed in the 54-card deck. We can consider those to see how the number of cards between them might work out.

Suppose we let J represent a joker, and - represent any other card. The numbers of interest can be found as follows:

For jokers: JJ---... there are 0 cards between. This will be the case also for ...

  -JJ---...

  --JJ---...

and so on, down to ...

 ...---JJ

The first of these adjacent jokers can be in any of 53 positions. So, the probability of 0 cards between is 53/1431.

__

For jokers: J-J---..., there is 1 card between. The first of these jokers can be in any of 52 positions, so the probability of 1 card between is 52/1431.

__

Continuing in like fashion, we find the probability of n cards between is (53-n)/1431. So, the expected number of cards between is ...

is there any photos or whatever?

x = -4

step-by-step explanation:

- 20 - 4(x + 3) = 4x

=> -20 - 4x - 12 = 4x

=> - 32 -4x = 4x

=> -32 = 4x + 4x

=> - 32 = 8x

=> -32/8 = x

=> -4 = x