已知一纸箱中放有大小均匀的x只白球和y只黄球,从箱中随机地取出一只白球的概率是 . (1) 写出y与x的函数关系式; (2) 当x=10时,再往箱中放进20只白球,求随机地取出一只黄球的概率P. 答案:依题意,得: 整理得:
由(1)知当当 时, ∴取得黄球的概率() 11. —Do you mind me smoking here?— . Look at the sign. It says, “No smoking." A. It doesn’t matter B. Certainly not C. Never mind D. Better not