从一个正态总体中随机抽取一个容量为100的样本,其均值和标准差分别为81和12。构造总体均值的99%的置信区间为( )
A. 81±1.97
B. 81±2.35
C. 81±3.10
D. 81±3.52
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Look back at the reading passage “Into the Unknown” on pages 132-133. Decide whether each piece of information is a fact or speculation.how blue holes are formed _________
A. fact
B. speculation
Look back at the reading passage “Into the Unknown” on pages 132-133. Decide whether each piece of information is a fact or speculation.the depth of Dean's Blue Hole_________
A. fact
B. speculation
Look back at the reading passage “Into the Unknown” on pages 132-133. Decide whether each piece of information is a fact or speculation.what the remipede looked like in the past_________
A. fact
B. speculation
Look back at the reading passage “Into the Unknown” on pages 132-133. Decide whether each piece of information is a fact or speculation.the types of life that we can find on Europa _________
A. fact
B. speculation