MathCastle
Counting & ProbabilityHardExpected Value, Linearity & Advanced Probability

Expected Value, Linearity & Advanced Probability · Hard problem

The numbers 1,2,…,1001,2,\dots,100 are arranged in a uniformly random order. Find the expected value of the position (slot 11 through 100100) occupied by the number 11.

The answer is a fraction mn\tfrac{m}{n} in lowest terms; find m+nm + n.