Question

The life expectancy of computer terminals is normally distributed with a mean of 4 years and a standard deviation of 1 year. What is the probability that a terminal will last 5 years or less?

Answer 1

The probability that a terminal will last 5 years or less is 0.8413

Explanation:

Given:

μ= 4 years

σ= 1 year

Z=(x-μ)÷σ

Z=(5-4)÷1 = 1

The standard normal distribution table provides the probability that a normally distributed random variable Z, with mean equal to 0 and variance equal to 1, is less than or equal to z.

For z= 1 ⇒ P(z≤1)=0.8413