Dear Bharat:
Good day and thanks for your message!
Actually PMBOK does mention both of the concepts. So if a question is asking about an estimate and not mentioning which technique to follow (directly or indirectly), I would recommend going for the PERT estimate as it puts more weight on the most likely estimate. In the real PMP exam, you will not encounter a situation where a question asks for an estimate, doesn’t directly or indirectly points out to the required technique, and have both simple average and PERT estimates as the answers to two of the given choices. Such ambiguous questions are usually eliminated out of the exams. However, you will see such question in exam simulators and sample question banks on the internet, as the idea there is to have more difficult questions for the training and learning purposes.
I hope this answers your concern. Let me know if it doesn’t.
Regards,
Khurram Hussain, PMP, CSSBB