Variance of a union indicator

Three independent events each occur with probability 0.50.5. Let XX be the indicator that at least one of the three occurs. What is Var(X)\operatorname{Var}(X)? (to 3 decimals)

Show hints (2)+
  1. First get q = P(at least one) via the complement 1 - P(none) = 1 - 0.5^3.
  2. An indicator's variance is q(1-q).

Answer

Reveal answer →

0.109 (± 0.001)

Want the full step-by-step worked solution? It's part of Premium - along with a worked solution for every question in the bank.

Asked at: Timed Mental-Math & Sequences, Game-Based Aptitude

Related questions