# Exercise to calculate the probability of finishing a project on timeProbability Calculator - PERT Method

### Problem Data

It is required to calculate **The probability that the project will be completed in less than 40 days** according to the following data:

- Expected Project Time (T
_{E}) - 36.3333 days
- Project Variance (σ
^{2}) - 5.2221
- Description
**Exercise to calculate the probability of finishing a project on time**You have a project with an expected completion time of 36.333 days and a variance of 5.2221. You want to know the probability of completing the project in less than 40 days.

## Solution

The following are the detailed calculations and graphs to obtain **The probability** according to the data provided:

### Step 1:

The **PERT Method** is based on two assumptions:

- Project completion times follow a normal probability distribution.
- The times of the activities are statistically independent.

From these assumptions, the normal distribution curve (bell curve) is used to represent the project completion dates. This distribution will indicate that the project has a 50% probability of finishing before the Expected Time (T_{E} = 36.3333 days) and a 50% probability of exceeding the Expected Time.

To calculate **The probability that the project will be completed in less than 40 days** we will do the following:

Also:

Where:

**T:**Due date to be evaluated.**σ:**Project Standard Deviation. It is obtained from the square root of the Variance.

Replacing the values we would have:

**Note:** The normal distribution table is used to calculate this value.

The probability that the project will be completed in less than 40 days es **0.9457**

## Learn with step-by-step explanations

At PM Calculators we strive to help you overcome those tricky subjects in an easier way.

### Membership

With access to our membership you will have access to 13 applications to learn projects, linear programming, statistics, among others.

#### What calculators are included?

Critical Path PERT and CPM

Linear Programming Methods

Normal Distribution

Break-even and more

Purchase our monthly subscription from

Learn more and save with semi-annual, annual and lifetime plans.