Whose draw is larger?

MediumProbability~6m

Jimmy picks a number uniformly at random from {1,2,…,1000}\{1, 2, \dots, 1000\} and, independently, Simon picks uniformly from {1,2,…,3000}\{1, 2, \dots, 3000\}. What is the probability that Simon's number is strictly larger than Jimmy's?

Show hints (2)+
  1. Condition on Jimmy's value jj: P[Simon>j]=(3000−j)/3000\mathbb{P}[\text{Simon}>j]=(3000-j)/3000.
  2. Average over j∈{1,…,1000}j\in\{1,\dots,1000\} using ∑j=11000j=1000⋅10012\sum_{j=1}^{1000} j=\tfrac{1000\cdot1001}{2}.

Answer

Reveal answer →

0.8332 (± 0.002)

Create a free account to see the full worked solution and track your progress.

Interview format: Hedge Fund Quant, Prop Trading

Related questions