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【简答题】
为了解甲、的产品质量，采用分层抽样的方法从甲、生产的产品中分别抽出取14件和5件，测量产品中的微量元素x，y的含量（单位：毫克）。下表是的5件产品的测量数据： （1）已知甲厂生产的产品共有98件，求生产的产品数量； （2）当产品中的微量元素x，y满足x≥175，且y≥75时，该产品为优等品。用上述样本数据估计生产的优等品的数量； （3）从抽出上述5件产品中，随机抽取2件，求抽取的2件产品中优等品数ξ的分布列极其均值（即数学期望）。
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