mscroggs.co.uk
mscroggs.co.uk

subscribe

Puzzles

The ace of spades

I have three packs of playing cards with identical backs. Call the packs A, B and C.
I draw a random card from pack A and shuffle it into pack B.
I now turn up the top card of pack A, revealing the Queen of Hearts.
Next, I draw a card at random from pack B and shuffle it into pack C. Then, I turn up the top card of pack B, revealing another Queen of Hearts.
I now draw a random card from pack C and place it at the bottom of pack A.
What is the probability that the card at the top of pack C is the Ace of Spades?

Show answer

Archive

Show me a random puzzle
 Most recent collections 

Advent calendar 2019

Sunday Afternoon Maths LXVII

Coloured weights
Not Roman numerals

Advent calendar 2018

Sunday Afternoon Maths LXVI

Cryptic crossnumber #2

List of all puzzles

Tags

spheres planes rugby coins crossnumber addition chess dates multiplication rectangles christmas division colouring triangles pascal's triangle quadratics menace scales arrows money symmetry taxicab geometry 3d shapes triangle numbers perimeter calculus trigonometry lines unit fractions sum to infinity digital clocks ave square roots squares irreducible numbers dodecagons ellipses integers sport gerrymandering books percentages functions doubling polygons square numbers median number grids sums indices differentiation clocks averages speed the only crossnumber partitions cryptic crossnumbers remainders mean shape digits regular shapes cards odd numbers parabolas games numbers factorials proportion prime numbers elections fractions bases perfect numbers advent balancing products time dominos folding tube maps area crosswords wordplay palindromes chocolate 2d shapes circles routes means floors complex numbers people maths factors geometry coordinates cube numbers chalkdust crossnumber integration star numbers dice multiples sequences algebra hexagons probabilty graphs logic shapes cryptic clues crossnumbers probability surds volume range angles tiling

Archive

Show me a random puzzle
▼ show ▼
© Matthew Scroggs 2012–2020