Communication Channels Exam Question - Answer doesn't make sense

The answer is 35. But I get 45. Not sure why it's 35.

You are the project manager for the ABC Project. Initially you have identified 5 stakeholders in your project. As the project moved ahead, 5 more stakeholders got involved in the project.

Assuming that they all need to communicate with each other, how many additional communication channels are there?

Choose one answer.
A. 5 Incorrect
B. 45 Incorrect
C. 35 Correct
D. Cannot be evaluated Incorrect
Marks for this submission: 0/1.

First place 5 stakeholders, so number of communication channels are, 5x4 = 20 then 20/2 so answer is 10. Alright...!

Now after additions of five (5) more stakeholders, the total stakeholders are ten (10) now. So calculate the resulted number of channels, and that will be, 10x9 = 90/2 = 45.

Since question is asking 'additional' so:
new number of communication channels - existed ones. Means 45 - 10 = 35.

Therefore, the correct answer is 35.

Makes sense...?

Wow that was good PMBOY. Well done! You will definitely pass this exam.

Curious why the PM was not included in the calculation.

For your information "anitkhagram", PMPBOY has already earned his PMP Credential in July 2011 in first attempt itself so does not need to pass this exam again.

PMPBOY comes here to help PMP aspirants as PMPBOY is a professional PMP Instructor. Of course, depending on the context, his services maynot be free...!

If you use n(n-1)/2 you get 10(9)/2 = 45.

The question should include the PM which would drive the answer higher. But the answer is lower. 35. huh?

i am curious to know why the pm himself is not included...?

I do not see where exactly it is explicitly mentioned that the PM did not count herself/himself initially as one of the five stakeholders in the question.