Ximpledu

Sampling Distribution

See how to find the mean, variance, and standard deviation of the mean of a sample.
1 example and its solution.

Sampling Distribution

Formula

Population
N(x, σ2)




Sample

E(X) = x
V(X) = σ2n
σ(X) = σn
Population:
Total group of values
N(x, σ2): Normal Distribution
Sampling:
Picking n values from the population
(= sample size: n)

X: Mean of the sample values

E(X): Expected Value of X
V(X): Variance of X
σ(X): Standard deviation of X

Example

Books in a library
Mean: 250 pages
Standard deviation: 20 pages
Normal distribution
If you randomly pick 25 books,
P([mean of the pages of the books] ≥ 256 pages) = ?

zP(0 ≤ Z ≤ z)
0.50.1915
10.3413
1.50.4332
20.4771
Solution