题目
Problem
A random sample of 10 newborn baby boys is taken and their masses in kg are recorded. From this sample, the population standard deviation of all newborn baby boys is estimated as . A random sample of 5 newborn baby girls is taken and their masses in kg are recorded as follows.
It is assumed that the masses of newborn baby boys and girls have the same population standard deviation, .
By pooling the two samples, calculate an estimate of .
[4]
题目中文翻译
随机抽取 10 名新生男婴，并记录他们的体重（单位为 kg）。由该样本估计所有新生男婴总体的标准差为 。随机抽取 5 名新生女婴，并记录她们的体重（单位为 kg）如下。
假设新生男婴和女婴的体重具有相同的总体标准差 。
通过合并两个样本，计算 的估计值。