作者slouming (*slou-ming*)
看板TransPSY
標題[統計] 一個統計問題，求解~拜託了!
時間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
不知道在這裡發問適不適合
如果不適合 會自D
但是我怎麼算都求不出來
而且這題目是老師自己出的
也沒有所謂的解答
老師只是要我們自己想一想要怎麼求解
真的很想要知道答案
拜託大家了...
謝謝
--
※ 發信站: 批踢踢實業坊(ptt.cc)
◆ From: 220.134.37.231
1F：→ skylikewater:(a) 常態+常態=常態吧 meanY=60, varY=64 01/04 03:42
2F：→ skylikewater:(b) z score=+-0.125 查z表 01/04 03:43
3F：→ skylikewater: 還是應該查t表 df=150啊.... 01/04 03:44
4F：→ skylikewater:(c) 應該就是查z score=0.25了吧 我也是嘗試寫的 01/04 03:45