Insight · ★★★☆☆ · ~5 min
The Double Heads Count
Flip 10 coins; expected count of adjacent HH pairs?
by MindYourPuzzle
A fair coin is flipped 10 times. A "double head" (HH) is any consecutive pair of flips that are both heads. Note: in HHH, there are 2 double heads.
What is the expected number of double heads?
Hints