STATISTICS

2008-05-16 7:00 pm

Q1: A random sample of 36 students shows an average age of 24 years old with a know population standard deviation of 6 years , The standard error of the ssample means is ? (how to calcaulate)

Q2: The probability of obtaining a sample mean large than 26 is ? (how to calcaulate ?)

回答 (2)

Adelmen

2008-05-16 9:56 pm

✔ 最佳答案

Q.1

Since the sample size greater than 30, the random variable (age) follows Normal Distribution.

Standard Error of the Sample Mean

= Z(elva/2) * Standard Deviation / Square Root of n

= Z(elva/2) * 6/ square root of 36

= Z(elva/2)

Q.2

P(X greater than 26)

= P(Z greater than (26-24)/(6/square root of 36) )

= P(Z greater than 2)

= 0.022750132

2008-05-17 20:51:41 補充：
The probability of uncertainty (elva).
Find your answer from normal table with respect to different elva.
e.g. elva = 0.05, Z(elva/2) = 1.96
elva = 0.1, Z(elva/2) = 1.645

👍 0 👎 0

[匿名]

2008-05-19 9:19 pm

唔該哂...謝謝

👍 0 👎 0