In: Statistics and Probability
A population of values has a normal distribution with μ=238.6
and σ=54. You intend to draw a random sample of size n=128
Find P84, which is the mean separating the
bottom 84% means from the top 16% means.
P84 (for sample means) = ___________
Given that,
mean = = 238.6
standard deviation = = 54
n = 128
= 238.6
= / n = 54 /128=4.77
Using standard normal table,
P(Z < z) = 84%
= P(Z < z) = 0.84
z =0.99 Using standard normal table,
Using z-score formula
= z * +
= 0.99*4.77+238.6
= 243.32