Question

A population of values has a normal distribution with μ = 49.1 and σ = 29.4 . You intend to draw a random sample of size n = 35 . Find P4, which is the mean separating the bottom 4% means from the top 96% means. P4 (for sample means) =

Answer 1

Solution

Given that,

mean = = 49.1

standard deviation = = 29.4

n = 35

=   = 49.1

= / n = 29.4 / 35 = 4.97

Using standard normal table,

P(Z < z) = 4%

= P(Z < z) = 0.04  

= P(Z < -1.751) = 0.04

z = -1.751

Using z-score formula  

= z * +

= -1.751 * 4.97 + 49.1

= 40.4