For each 6-month period during a light bulb's life span, the odds of it not burning out from over-use are half what they were in the previous 6-month period. If the odds of a light bulb burning out during the first 6-month period following its purchase are 1/3, what are the odds of it burning out during the period from 6months to 1 year following its purchase? Choose the correct choice from the following options.
A) 5 / 27  B) 2 / 9  C) 1 / 3  D) 4 / 9  E) 2 / 3

Rationale: "probability of not burning out during the first 6 months 1 - 1 / 3 = 2 / 3 probability of not burning out during the next 6 months 2 / 3 / 2 = 1 / 3 , hence probability of burning out 1 - 1 / 3 = 2 / 3 . probability of burning out during the period from 6 months to 1 year = probability of not burning out in first 6 months * probability of burning out in next 6 months = 2 / 3 * 2 / 3 = 4 / 9 answer : d ."
Answer: D