【推荐1】为考查某校高二男生的体重，随机抽取44名高二男生，实测体重数据(单位：kg)如下：
57，61，57，57，58，57，61，54，68，51，49，64，50，48，65，52，56，46，54，49，51，47，55，55，54，42，51，56，55，51，54，51，60，62，43，55，56，61，52，69，64，46，54，48
将数据进行适当的分组，并画出相应的频率分布直方图和频率分布折线图．

【推荐3】下面是一批检波器测量噪声（噪声电平）的100个观测值（单位：mV，真值为以下数据乘以10），试作出这些数据的频率直方图，判断其是否服从正态分布，再估计噪声在区间上的概率．
0.1               -1.0             1.9             -0.1             0.0             0.3             -1.2             0.0             -0.4             0.1
1.5             0.3             1.0               -1.3             0.5               -1.2        -3.4        -3.0        -0.5             1.9
0.2             0.1             0.7               1.3             2.4               -0.5             0.5               -3.5             0.4             0.7
2.0               -0.4             -1.3             -1.9        -0.5             -1.5             -0.1             -1.1             0.0             0.2
-2.3             0.5             0.7               -2.1        -0.6             -0.4             2.4             1.5             1.6             0.6
-0.1             0.5               -0.1             1.1             2.5               -2.6        -0.3             1.2               -0.8        -2.4
0.7             1.2             0.5             0.0               -0.5        -0.3        -1.8             0.2               -1.9        -0.8
-0.4        -1.1             2.9             -1.1             0.4             0.0             -0.4             -0.3             1.7               -1.5
-1.0             1.1             0.0             -1.1             0.9             1.7             -0.3             2.1             0.7             0.7
-0.6             2.3             2.0               -1.1             1.2             1.0             0.1               -0.5        -0.3             -0.2

【推荐3】统计某班同学一次考试的数学成绩，得到如下频率分布直方图，已知该班学生数学成绩不低于80分的频率为0.60.

   

(1)求频率分布直方图中，的值；
(2)估计该班学生数学成绩的平均分和中位数.