作业帮：find interval 很着急
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：find interval 很着急
suppose that a large international corporation wishes to obtain its own "benchmark" for one day travel expenses in moscow.to do this .it records the one day travel expenses for a random sample of 35 executives visiting Moscow.The mean and the standard deviation of these expenses are calculated to be x =$538 and s =$41.futhermore ,a histogram shows that the expenses are approximately.
A:find an interval that we estimate contains 99.73 persent of all one day travel expenses in Moscow.
B:if an executive submits an expense of $720 for a one day stay in Moscow ,should this expense be considered unusully high?why or why not?
suppose that a large international corporation wishes to obtain its own "benchmark" for one day travel expenses in moscow.to do this .it records the one day travel expenses for a random sample of 35 executives visiting Moscow.The mean and the standard deviation of these expenses are calculated to be x =$538 and s =$41.futhermore ,a histogram shows that the expenses are approximately.
A:find an interval that we estimate contains 99.73 persent of all one day travel expenses in Moscow.
B:if an executive submits an expense of $720 for a one day stay in Moscow ,should this expense be considered unusully high?why or why not?
A,这就是让你找正态分布图中间区域的区间.他的面积是99.73,那么你可以找它的一半,49.865,可以得出任意一边的空白部分面积就是0.135.然后你去附录正态分布表里这个面积值对应的Z值.这个点到(1-Z)就是关于Z的区间.中间需要X和Z的转换,这个就不用我说了吧楼主?就是套公式,z=(X-Xba)/标准差.
B,这个就是考你概念”寻常”与否的.超过两个标准差就算是不寻常.楼主可以用上面的结果尝试一下.不会再问我.
再问： 高人你能用英语帮我答一下么......
再答： 你是想要这道题目的英语打法？还是说你要我用英语解释给你听这个题目应该怎么回答？？
再问： 英语答法...谢谢......
再答： Okay, no problem!This is a question talking about normal distribution, in which we are supposed to find part A,an interval for a certain percentage. and also to determine part B,where a valiabe with a fixed value in this distribution is usual or not. following is the working:
For part A, the area (percentage) is given, which is 0.9973(99.73%).From the normal distribution chart, shown below, we can easily find that Z-score is actually 2.78, which is at the right side of standard normal distribution graph. Now we need to convert this Z-score to variable represented by X. The formula is as: Z=(x-x)/s, which reads as Z equals to X minus X ba, whole thing divided by the mean x. so do a conversion, we get X=Z*s+x. We already know Z=2.78. so X=2.78*41+538=651.98. Hece, the interval is (0,652). which is to say, in this interval (0.652), we estimate it contains 99.73 persent of all one day travel expenses in Moscow.
For part B, first of all, the definition for unusual evens is that the variable is more than 2 standard deviation away from centre (where it is at Z=0 or x=x). hence ,we need to find 2s=82, then find the exact value (hign value for this question) which is x+2s=538+82=620. which means 720 is greater than 2 standard deviation. Hence 720 is considered unusual high.
This is the answer for this question, which I spent quite a long time to type. Please take it as the best answer :)楼主这可是我花时间打出来的哟，希望采纳 ：）
this is the standard normal distribution chart...
B,这个就是考你概念”寻常”与否的.超过两个标准差就算是不寻常.楼主可以用上面的结果尝试一下.不会再问我.
再问： 高人你能用英语帮我答一下么......
再答： 你是想要这道题目的英语打法？还是说你要我用英语解释给你听这个题目应该怎么回答？？
再问： 英语答法...谢谢......
再答： Okay, no problem!This is a question talking about normal distribution, in which we are supposed to find part A,an interval for a certain percentage. and also to determine part B,where a valiabe with a fixed value in this distribution is usual or not. following is the working:
For part A, the area (percentage) is given, which is 0.9973(99.73%).From the normal distribution chart, shown below, we can easily find that Z-score is actually 2.78, which is at the right side of standard normal distribution graph. Now we need to convert this Z-score to variable represented by X. The formula is as: Z=(x-x)/s, which reads as Z equals to X minus X ba, whole thing divided by the mean x. so do a conversion, we get X=Z*s+x. We already know Z=2.78. so X=2.78*41+538=651.98. Hece, the interval is (0,652). which is to say, in this interval (0.652), we estimate it contains 99.73 persent of all one day travel expenses in Moscow.
For part B, first of all, the definition for unusual evens is that the variable is more than 2 standard deviation away from centre (where it is at Z=0 or x=x). hence ,we need to find 2s=82, then find the exact value (hign value for this question) which is x+2s=538+82=620. which means 720 is greater than 2 standard deviation. Hence 720 is considered unusual high.
This is the answer for this question, which I spent quite a long time to type. Please take it as the best answer :)楼主这可是我花时间打出来的哟，希望采纳 ：）
this is the standard normal distribution chart...