In: Statistics and Probability
How to solve for X with a mean = 9, deviation = 3 and a sample size of 25, P( sample mean > 8) is
Population mean, µ = 9
Population standard deviation, σ = 3
Sample size, n = 25
P( x̅ > 8)
= P( (x̅-μ)/(σ/√n) > ( 8 - 9 )/(3/√25 ) )
= P( z > -1.6667
)
= 1 - P( z <
-1.6667)
Using excel
function:
= 1- NORM.S.DIST( -1.6667 ,
1)
=
0.9522