Thermodyne Engineering Systems interview questions

we had a exam of appitude test as the first round and later they shortlisted based on the marks we had a exam of appitude test as the first round and later they shortlisted based on the marks

It's a very long process. HR has given me time at 10:00 am. Suddenly HR went to home and the interview has been suspended. After 2 hours again an HR came and asked me to solve some questions, which as much easy that a 9th standard student can also solve. After again a waiting period of 2 hours. Then the HR asked me about my job preferences. Next again 2 hours of waiting and then CEO has interviewed me followed by an employee. In this round they have asked me some engineering basics mostly related to HMT, Fluid Mechanics and Thermodynamics. The questions are easy to medium standard. There after 1 hour later the former HR has called me over phone and conveyed me that my department will be production and salary is around 10K. After six months of probation period they will give me a hike, which is completely based on my performance. I am a GATE qualified student, so must expect minimum 20K to 25K, because with my GATE score only I can easily get M.Tech in IIT Roorkee. So there I can get Rs.12500 stipend. Why should I accept this offer after a long interview process.