when fair coin is tossed 9 times find the probability of getting head at least once.  Select the correct option:
A) 1 / 512 B) 511 / 512 C) 9 / 512 D) 503 / 51 E) 503 / 510

Rationale: 1 - 1 / 2 ^ 9 = 1 - 1 / 512 = 511 / 512 answer : b
Answer: B