Skip to content / Đến nội dung
ThichHocToan.com

2019 AMC 10B Question 17

AMC10 · 2019 AMC 10B

Question 17

A red ball and a green ball are randomly and independently tossed into bins numbered with the positive integers so that for each ball, the probability that it is tossed into bin $k$ is $2^{-k}$ for $k = 1,$ $2,$ $3,$ $\ldots.$ What is the probability that the red ball is tossed into a higher-numbered bin than the green ball?
  1. $ \dfrac{1}{4} $
  2. $ \dfrac{2}{7} $
  3. $ \dfrac{1}{3} $
  4. $ \dfrac{3}{8} $
  5. $ \dfrac{3}{7} $