某批乒乓球的质量检验结果如下：

（1）画出这批乒乓球“优等品”频率的折线统计图；

（2）这批乒乓球“优等品”的概率的估计值是多少？

（3）从这批乒乓球中选择5个黄球、13个黑球、22个红球，它们除颜色外都相同，将它们放入一个不透明的袋中．

①求从袋中摸出一个球是黄球的概率；

②现从袋中取出若干个黑球，并放入相同数量的黄球，搅拌均匀后使从袋中摸出一个是黄球的概率不小于$\frac{1}{3}$，问至少取出了多少个黑球？

    It was a hot summer day. The sun was shining brightly and all could think of was1down with a scoop of my favorite ice cream. I decided to make a quick2to the newly opened ice cream parlor (冰淇淋店) close by for a mid-day3.

    As soon as I arrived there, I 4my ice cream in a fancy cone and asked the server to5two tubs of chocolate ice cream for folks at home.

    While waiting for my take-out, I was halfway through my icy treat and was enjoying the view of the two colorfully6ice cream flavors, sitting pretty one next to the other.

    Now that my to-go order was7, I headed to the payment counter to settle the bill. Surprisingly, the cashier had forgotten to8my ice cream,9only for the two tubs.

    The next few10passed by as I11between doing what was easy—clearing the bill and moving out, and doing what was right—12 the error. I knew if I didn't bring the error in the bill to his13, my ice cream would be charged against his14.

    That moment, my decision was made and I went and told him what he had 15. He looked at me in 16 and thanked me profusely for telling the error. Had it not been for my 17telling the error, he would have been 18. The smile of relief on his face made me smile, too.

    I came out of the ice cream parlor feeling really19about myself. I knew that day how wonderful it feels to do what is right20what is easy.

某工厂排放的污水中含有树叶、碎塑料薄膜、泥沙，还具有一定的臭味，需对其进行净化处理转化为清洗用水。请回答下列有关问题：