$begingroup$ For (a), a straightforward way to have a look at is that you've got lessened your probability Place to just the mixtures that have not less than just one boy: 知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 (the next equality takes place because the probabilities are the same for odd and perhaps figures, https://pgsector14gurugram.blogspot.com/2025/07/book-affordable-1-rk-for-rent-in.html