【简答题】为了解某校高中学生的视力情况,对该校学生按年级进行分层抽样调查,已知该校高一、高二、高三分别有学生800名、600名、500名,若高三学生共被抽取25名,则高一年级应被抽取的学生数为 .
【简答题】某厂生产A、B、C三种产品,其所需劳动力、材料等有关数据见下表。 要求: (a)确定获利最大的产品生产计划; (b)产品A的利润在什么范围内变动时,上述最优计划不变; (c)如果设计一种新产品D,单件劳动力消耗为8单位,材料消耗为2单位,每件可获利3元,问该种产品是否值得生产?
【单选题】某校期末考试后,为了分析该校高一年级1000名学生的学习成绩,从中随机抽取了100名学生的成绩单,就这个问题来说,下面说法正确的是( )
【单选题】Qufu is _____________________
A.
birthplace of traditional Chinese culture
B.
political, economic and cultural center , City of Springs
C.
a beautiful seaside city,beer,good weather,fine beaches
D.
Penglai Pavilion, the story of the Eight Immortals
E.
the leader of Five Scared Mountains, 30 old temples and 66 scenic spots
【单选题】Taian is _________
A.
birthplace of traditional Chinese culture
B.
political, economic and cultural center , City of Springs
C.
a beautiful seaside city,beer,good weather,fine beaches
D.
Penglai Pavilion, the story of the Eight Immortals
E.
the leader of Five Scared Mountains, 30 old temples and 66 scenic spots
【单选题】Mount Tai is _____________________
A.
birthplace of traditional Chinese culture
B.
political, economic and cultural center , City of Springs
C.
a beautiful seaside city,beer,good weather,fine beaches
D.
Penglai Pavilion, the story of the Eight Immortals
E.
the leader of Five Scared Mountains, 30 old temples and 66 scenic spots
【单选题】某校期末考试后,为了解该校高一年级1000名学生的学习成绩,从中抽取了100名学生的成绩单进行分析,就这个问题来说,下面说法中正确的是 [ ]
【简答题】Traditional springs and
dampers are referred to as passive suspensions. If the suspension is externally
controlled then it is a semi-active or active suspension.
【单选题】为了使在航线飞行的飞机保持规定的高度,必须按照( )来设定气压式高度表。