作者slouming (*slou-ming*)
看板TransPSY
标题[统计] 一个统计问题，求解~拜托了!
时间Mon Jan 3 22:56:28 2011
If x1, x2, x3 are three normally and independently distributed random
variables with means 7, 28, 6, and variances 4, 12, 4, respectively.
Suppose y = 2x1 + x2 + 3x3
(a) Find the distribution of y and its parameters.
(b) If a random sample of size 150 taken from the distribution of y, find
the probability of sample mean (X-Bar)lies between 59 and 61.
(c) Find the probability of sample mean (X-Bar) exceeds 62
不知道在这里发问适不适合
如果不适合 会自D
但是我怎麽算都求不出来
而且这题目是老师自己出的
也没有所谓的解答
老师只是要我们自己想一想要怎麽求解
真的很想要知道答案
拜托大家了...
谢谢
--
※ 发信站: 批踢踢实业坊(ptt.cc)
◆ From: 220.134.37.231
1F：→ skylikewater:(a) 常态+常态=常态吧 meanY=60, varY=64 01/04 03:42
2F：→ skylikewater:(b) z score=+-0.125 查z表 01/04 03:43
3F：→ skylikewater: 还是应该查t表 df=150啊.... 01/04 03:44
4F：→ skylikewater:(c) 应该就是查z score=0.25了吧 我也是尝试写的 01/04 03:45