MathDB
TOT 101 1985 Autumn J5 two throw coins.10-11 times, more heads

Source:

August 26, 2019
combinatoricsprobability

Problem Statement

Two people throw coins. One throws his coin 1010 times, the other throws his 1111 times . What is the probability that the second coin fell showing "heads" a greater number of times than the first?
(For those not familiar with Probability Theory this question could have been reformulated thus : Consider various arrangements of a 2121 digit number in which each digit must be a " 11 " or a "22" . Among all such numbers what fraction of them will have more occurrences of the digit "22" among the last 1111 digits than among the first 1010?)
(S. Fomin , Leningrad)