Question

The ages of subscribers to a certain newspaper are normally distributed with mean 35 years and standard deviation 5. What is the probability that the age of a random subscriber is more than 40 years?

Answer 1

0.1587

Explanation:

Applying,

P(μ>40) = P(μ-(x-μ)/σ)............. Equation 1

Where P(μ>40) = probability of the age of the random subscriber more than 40 years μ = mean, σ = standard deviation, x = random subscriber

From the question,

Given: μ = 35 years, σ = 5 years, x = 40 years.

Therefore,

P(μ>40) = P(35-(40-35)/5) = P(35-(5/5)

P(μ>40) = 1-φ(1)

From the norminal probabilty table,

P(μ>40) = 1-0.8413

P(μ>40) = 0.1587