Question

A box has 1024 fair and 1 two-headed coin. You pick a coin randomly, make 10 flips and get all H. (a) You flip the same coin you picked 100 times. What is the expected number of H? (b) You flip the same coin you picked unitl you get H. What is the expected number of flips you make?

Answer 1

(a) Expected number of H is 100 as it is very likely the coin is the two headed coin as it is rare to get 10 heads for all 10 tosses.

(b) 1. As the coin is the two headed coin, you will get a head on the first toss.

Explanation: