The sample space listing the eight simple events that are possible when a couple has three children is {bbb, bbg, bgb, bgg, gbb, gbg, ggb, ggg}. After identifying the sample space for a couple having four children, find the probability of getting four girls and no boys. Identify the sample space for a couple having four children (Use a comma to separate answers as needed.) Find the probability of getting four girls and no boys. (Type an integer or a decimal. Do not round.)