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

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

Archive

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