Geometry: John has 3 unique coins such that the probability of obtaining a head when the coin is flipped is 110, 210 and 310, respectively. If he flips each of the 3 coins once, the probability that at least 1 heads appears is p. What is the value of 1000p? I have n fair coins and toss them all up together. Let the number of heads I get be X. My friend, Bob has (n+k) fair coins and he tosses them together too to get Y number of heads. What is probability that P (X >Y)?