# 4 Steps to Solve PDM PMP Questions

## How do you Solve a Precedence Diagramming Method PMP Questions?

You will find a number Precedence Diagramming Method (PDM) Questions in the PMP Exam. I have noticed that, some PMP aspirants find these questions difficult to solve. Even though the underlying concept is easy and most of the aspirants understand it well, but still they get confused by such questions.

In my opinion, PDM PMP questions are easy to solve. But, sometimes they are worded in difficult and convoluted manner. If you decipher the wordings of such questions, you can confidently answer them.

### Precedence Diagramming Method

If you understand PDM, you can skip this section. Otherwise you should read the following articles before venturing ahead.

Precedence Diagramming Method is the most popular technique to depict  relationships between different Project Activities. PDM supports 4 type of logical Relationships. These are

PDM also supports two Modifiers – Leads and Lags. These Modifiers change the nature of the logical relationships.

### Logical Steps to Solve PDM PMP Questions

Let us understand how to solve PDM PMP Questions. We will look at an example of such a question and discuss the logical steps involved in solving the questions.

I received the following question in mail from one of my students. I do not know the source of the question. She found the question confusing. The question is worded to confuse the readers. The question is about determining the relationship between 2 activities. Let us look at the question.

After one year of construction, an office building is scheduled to be completed on 30th January. The landscaping work needs to start 15 days prior to completion of the building. Which of the following relationships most likely represents the relationship of the start of landscaping work to the completion of the office building?

2. Start-to-finish with a 15 day lead
4. Start-to-finish with a 15 day lag

This is an excellent question. You may find 2-3 PDM PMP questions in the exam. These type of questions can be easily solved by following the 4 logical steps:

1. Determine the Activities in the question
2. Determine the Dependency between the Activities i.e. which activity is dependent on which other activity
3. Determine which activity(ies) are Finishing and which are Starting
4. Determine the Modifier between the Activities

Let us read the question again.

After one year of construction, an office building is scheduled to be completed on 30th January. The landscaping work needs to start 15 days prior to completion of the building. Which of the following relationships most likely represents the relationship of the start of landscaping work to the completion of the office building?

You need to identify the relevant phrases of a PMP question to answer it correctly. I have highlighted the relevant phrases in green color. Let us now follow 4 logical steps to solve our question.

#### Step 1 – Determine Activities

In this question there are 2 Activities. These are

X – landscaping work
Y – the (office) building

#### Step 2 – Determine Dependency

Is “X dependent on Y” or is “Y dependent on X”?

Let us read the question again. It says that “landscaping work needs to … of the building”. Clearly X is dependent on Y. You should not get confused by the words like ‘Start’ or ‘Completion’ while determining the dependency. Dependency is between 2 activities while Start and Finish are events of these activities. In PDM parlance we can say that X is the Successor and Y is the Predecessor.

#### Step 3 – Determine Start and/or Finish

Which Activity is finishing and which Activity is starting?

It is apparent from the question that X has to start while Y has to finish. So, the relationship between X & Y is Finish to Start (FS). In PDM notation the predecessor’s event comes first and it is followed by the successor’s event.

#### Step 4 – Determine Activity Modifier

This may be an optional step. Many relationships do not have a Lead or Lag modifier.

The question mentions X Starts prior to Y’s Finish. Or we can say that successor is starting before the predecessor. Or Successor is Leading the Predecessor.

Hence, the answer to the given question would be FS with a lead of 15 days – Option A.

Refer to the following figure for diagrammatic representation of the two activities in the question.

Click to Enlarge

### Conclusion

You should try to find Leading statements/phrases/words in the question as you read it. Only after that, you should proceed to the answer the question. You can also read my other article on general tips for answering PMP Questions. It provides general hints on solving PMP questions.

You should practice a lot of questions to succeed in the exam. There are no shortcuts to pass the exam. If you are looking for free PMP sample questions then you should look at 3000+ free PMP Sample Questions. If you are looking at some good sources for paid questions, then you can consider either PMP Exam Simulator by Cornelius Fichtner or PMP Practice Exams by Christopher Scordo. For complete details about my recommendation, you can look at my article that compares 6 popular PMP exam simulators.

However, before you buy any paid tests, you should read my article on 13 Reasons to Invest in a Paid PMP Practice Exam.

I hope you would be able to solve PDM PMP questions now. If you have any other similar questions, please leave them as a comment and I will answer them.

All the best.

You can refer to Project Management Lexicon to read standard definition of Precedence Diagramming Method.

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