统计学样本分布题目,英文,The mean of the weights of a large bunch of pencil is four times the standard deviation.If the weights of these pencils are normally distributed and the probability that the weight of a randomly chosen pencil is gre
来源：学生作业帮助网 编辑：六六作业网 时间：2024/11/22 04:07:14
统计学样本分布题目,英文,The mean of the weights of a large bunch of pencil is four times the standard deviation.If the weights of these pencils are normally distributed and the probability that the weight of a randomly chosen pencil is gre
统计学样本分布题目,英文,
The mean of the weights of a large bunch of pencil is four times the standard
deviation.If the weights of these pencils are normally distributed and the
probability that the weight of a randomly chosen pencil is greater than 5 grams is
0.028.
a.Twenty of these pencils are chosen at random and the mean of the sample is
calculated.Find the probability that this mean is between 3 and 4 grams.
统计学样本分布题目,英文,The mean of the weights of a large bunch of pencil is four times the standard deviation.If the weights of these pencils are normally distributed and the probability that the weight of a randomly chosen pencil is gre
Let the standard deviation be s,then the mean is 4s,and
P(X>5)=0.028 that is P((X-4s)/s>(5-4s)/s)=0.028 where (X-4s)/s is standard normal
Check the standard normal table,(5-4s)/s=1.911,hence s=0.846
The sample mean of twenty pencils is normally distributed with mean 4s=3.384 and standard deviation s/√20=0.189.
Then P(3
一大捆铅笔的重量均值为标准差的四倍，如果铅笔的重量服从正态分布，，且随机选择一支铅笔的重量超过5克的概率为0.028.
a随机抽出这批铅笔的20%，计算简单平均数，求出平均数在3克到4克之间的概率。