In: Statistics and Probability
A random sample size of n=10, population μ=65, σ=19.
Determine P(x<68.9)
Determine P(x ≥66.9)
Solution :
Given that,
mean = = 65
standard deviation = = 19
n = 10
= 65
= / n = 19 10 = 6.0083
a ) P( < 68.9 )
P ( - / ) < ( 68.9 - 65 / 6.0083)
P ( z < 3.9 / 6.0083 )
P ( z <0.65)
= 0.7422
Probability = 0.7422
b ) P ( 66.9 )
= 1 - P ( 66.9 )
= 1 - P ( - /) (66.9 - 65 / 6.0083)
= 1 - P( z 1.9 / 6.0083 )
= 1 - P ( z 0.32 )
Using z table
= 1 - 0.6255
= 0.3745
Probability = 0.3745