题干

一个口袋中有红球、白球共20只,这些球除颜色外都相同,将口袋中的球搅拌均匀,从中随机摸出一只球,记下它的颜色后再放回,不断重复这一过程,共摸了50次,发现有30次摸到红球,则估计这个口块中有红球大约多少只?(  )

A:8只 

B:12只

C:18只

D:30只

上一题 下一题 0.0难度 选择题 更新时间:2018-01-09 10:49:54

答案(点此获取答案解析)

B

同类题1

阅读下面一首古诗,完成小题。
                                                                                                                                          雁门太守行
                                                                                                                                               李贺
                                                                                                                      黑云压城城欲摧,甲光向日金鳞开。
                                                                                                                      角声满天秋色里,塞上燕脂凝夜紫。
                                                                                                                      半卷红旗临易水,霜重鼓寒声不起。
                                                                                                                      报君黄金台上意,提携玉龙为君死。