1 . 下面是北方某城市2018年1—2月的日平均气温（单位：℃）的记录数据：
             2                                                           7             8             9             
                                                            0             5                          
                                                                           
                                                                           
                                               0                          5                          
             2                                                    7             5                          
(1)将数据适当分组，并画出相应的频率分布直方图；
(2)试估计该城市1—2月的日平均气温在0℃以下的天数所占的百分比.