In: Statistics and Probability
Given a population with a mean of µ = 100 and a variance σ2 = 14, assume the central limit theorem applies when the sample size is n ≥ 25. A random sample of size n = 46 is obtained. What is the probability that 98.80 < x¯ < 100.92?
Solution :
Given that,
mean = 
 = 100
standard deviation = 
 = 3.7417
n = 46

= 
 = 100

= 
 / 
n = 3.7417/ 
46 = 0.5517
P( 98.80 < 
 < 100.92) = P((98.80 - 100) / 0.5517<(
- 
)
/ 
< (100.92 - 100) / 0.5517))
= P(-2.18 < Z < 1.67)
= P(Z < 1.67) - P(Z < -2.18) Using standard normal table,
= 0.9525 - 0.0146
= 0.9379
Probability = 0.9379