Where to star Project planning if inputs are 5FTEs, 6 month duration and 1000 hrs of work ?

I'm with you, Ruben.

My question to the interviewer would have been, "The five phases of a project are Initiate, Plan, Execute, Control and Closure. The Initiating Phase is where the organization commits to an effort that produces a product or service. So what did the organization commit to produce?"

If you have no idea what the organization committed to produce, then the number of FTEs, duration and so forth are nothing more than nonsensical talking points.

For example, maybe the organization committed to building and donating a dog house for the new bomb sniffing dog at the local police department. If that was the commitment, then the interviewer's data points in the original poster's case are worthless since one carpenter could probably build a very nice doghouse in a single day including putting a shingled roof with underlayment on it.

I've run into these sorts of questions before on interviews. It's usually the sign of a novice interviewer who has only a peripheral understanding of structured project management.

The way to deal with that question is to go to the starting point: What is the product or service we're supposed to produce with this project? A good interviewer should be able to state that in no less than five sentences; if not, you're dealing with an amateur in PM. In that case, go back to basics and formulate your answer in a structured manner based on Initiate, Plan, Execute, Control and Close. If nothing else, it will show you're thinking in an analytical, but methodical basis; not running out the door, so to speak, to 'do something'.

Yes, I realised that I told 160 hrs x 5 = 800 hrs so if we utilise all resource assuming all can contribute we can finish the project in 45 days and release the resources, if different skills needed we need to load/allocate resources based on task sequencing/skills required and release the resources as soon as they finish all of their task in the project. Ideal/wait time is loss for service provider.

Interviewer was so aragont not willing to take any counter question and also not accepted my explanation. He was expecting something which I was not sure about.

I even asked him Are you are expecting answer related to cost and budgeting...he said no....

Did you asked for the feedback? or they gave you the explanation?

Excellently put forward by Naomi Caietti

Yes , I asked for feedback he told me i'm not selected :-( apart from that no explanation