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2017 AMC 10A Question 18

AMC10 · 2017 AMC 10A

Question 18

Amelia has a coin that lands heads with probability $\frac{1}{3},$ and Blaine has a coin that lands on heads with probability $\frac{2}{5}.$ Amelia and Blaine alternately toss their coins until someone gets a head; the first one to get a head wins. All coin tosses are independent. Amelia goes first. The probability that Amelia wins is $\frac{p}{q},$ where $p$ and $q$ are relatively prime positive integers. What is $q-p?$
  1. $1$
  2. $2$
  3. $3$
  4. $4$
  5. $5$