若某计算机系统是由500个元器件构成的串联系统，且每个元器件的_爱下问搜题

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问题单项选择题

若某计算机系统是由500个元器件构成的串联系统，且每个元器件的失效率均为10^-7/h，在不考虑其他因素对可靠性的影响时，该计算机系统的MTBF为______小时。

A．2×10⁴

B．5×10⁴

C．2×10⁵

D．5×10⁵

答案

参考答案：A

解析：[要点解析]
根据题意，由500个元器件构成的串联计算机系统的总失效率为各元器件的失效率的和，即为500×10^-7/h=5×10^-5/h。
在不考虑其他因素对可靠性的影响时，由于计算机系统的平均故障间隔时间可定义为该系统失效率的倒数，因此该计算机系统的平均故障间隔时间(MTBF)为2×10⁴h。

完形填空

完形填空（共15小题；每小题1分，计15分）
There was a woman in Detroit, who had two sons. She was worried about them, especially（尤其） the younger one, Ben, because he was not doing well in school. Boys in his class played jokes on him because he seemed so    1   . The mother   2   that she would help her sons to do   3   in school by herself. She told them to go to the Detroit Public Library to   4   a book a week and do a book report for her.
One day, in Ben’s class, the teacher held up a rock and asked   5   anyone knew it. Ben put up his hand and the teacher let him   6   . “Why did Ben raise his hand?” all of his.
   7  whispered and wondered. “He    8 said anything. What could he possibly want to say?” To their surprise, Ben not only   9   the rock, but also said a lot about it. He   10  other rocks in its group and even knew   11  the teacher had found it. The teacher and the other students were   12 . Ben had learned this from doing one of his book   13   .
Later Ben became the   14   student of his class. When he finished high school, he went to Yale University and   15   became one of the best doctors in the United States.

单项选择题

三组以上某实验室指标的测量值服从正态分布且方差齐。任两组分别进行多次t检验代替方差分析，将会

A．明显增大犯第Ⅰ类错误的概率

B．使结论更加具体

C．明显增大犯第Ⅱ类错误的概率

D．使计算更加简便

E．提高检验效能