Statistics for Maintenance Modelling: Basic Probability Concepts

# Using Statistical Tables to Find the Probability of a Random Variable Having a Certain Value¤

Lets have a look at working out the probability that a random variable having a standard Normal Distribution will take on a value less than 1.72 shown graphically here.

First use the table which gives the probabilities that a standardised variable selected at random will be greater than a value of Z and look up the figure for 1.72. Click on the look-up table to see that the probability of a value greater than 1.72 is 0.0427.

Therefore, the probability that a value of less than 1.72 occurs is 1 - 0.0427 = 0.9573.